At the moment the v4l2_subdev_enable/disable_streams() functions call
fallback helpers to handle the case where the subdev only implements
.s_stream(), and the main function handles the case where the subdev
implements streams (V4L2_SUBDEV_FL_STREAMS, which implies
.enable/disable_streams()).

What is missing is support for subdevs which do not implement streams
support, but do implement .enable/disable_streams(). Example cases of
these subdevices are single-stream cameras, where using
.enable/disable_streams() is not required but helps us remove the users
of the legacy .s_stream(), and subdevices with multiple source pads (but
single stream per pad), where .enable/disable_streams() allows the
subdevice to control the enable/disable state per pad.

The two single-streams cases (.s_stream() and .enable/disable_streams())
are very similar, and with small changes we can change the
v4l2_subdev_enable/disable_streams() functions to support all three
cases, without needing separate fallback functions.

A few potentially problematic details, though:

- For the single-streams cases we use sd->enabled_pads field, which
  limits the number of pads for the subdevice to 64. For simplicity I
  added the check for this limitation to the beginning of the function,
  and it also applies to the streams case.

- The fallback functions only allowed the target pad to be a source pad.
  It is not very clear to me why this check was needed, but it was not
  needed in the streams case. However, I doubt the
  v4l2_subdev_enable/disable_streams() code has ever been tested with
  sink pads, so to be on the safe side, I added the same check
  to the v4l2_subdev_enable/disable_streams() functions.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 187 ++++++++++++++--------------------
 1 file changed, 79 insertions(+), 108 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 0d376d72ecc7..4a73886741f9 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -2106,6 +2106,13 @@ static void v4l2_subdev_collect_streams(struct v4l2_subdev *sd,
 					u64 *found_streams,
 					u64 *enabled_streams)
 {
+	if (!(sd->flags & V4L2_SUBDEV_FL_STREAMS)) {
+		*found_streams = BIT_ULL(0);
+		if (sd->enabled_pads & BIT_ULL(pad))
+			*enabled_streams = BIT_ULL(0);
+		return;
+	}
+
 	*found_streams = 0;
 	*enabled_streams = 0;
 
@@ -2127,6 +2134,14 @@ static void v4l2_subdev_set_streams_enabled(struct v4l2_subdev *sd,
 					    u32 pad, u64 streams_mask,
 					    bool enabled)
 {
+	if (!(sd->flags & V4L2_SUBDEV_FL_STREAMS)) {
+		if (enabled)
+			sd->enabled_pads |= BIT_ULL(pad);
+		else
+			sd->enabled_pads &= ~BIT_ULL(pad);
+		return;
+	}
+
 	for (unsigned int i = 0; i < state->stream_configs.num_configs; ++i) {
 		struct v4l2_subdev_stream_config *cfg =
 			&state->stream_configs.configs[i];
@@ -2136,51 +2151,6 @@ static void v4l2_subdev_set_streams_enabled(struct v4l2_subdev *sd,
 	}
 }
 
-static int v4l2_subdev_enable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
-					       u64 streams_mask)
-{
-	struct device *dev = sd->entity.graph_obj.mdev->dev;
-	int ret;
-
-	/*
-	 * The subdev doesn't implement pad-based stream enable, fall back
-	 * to the .s_stream() operation.
-	 */
-	if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
-		return -EOPNOTSUPP;
-
-	/*
-	 * .s_stream() means there is no streams support, so only allowed stream
-	 * is the implicit stream 0.
-	 */
-	if (streams_mask != BIT_ULL(0))
-		return -EOPNOTSUPP;
-
-	/*
-	 * We use a 64-bit bitmask for tracking enabled pads, so only subdevices
-	 * with 64 pads or less can be supported.
-	 */
-	if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
-		return -EOPNOTSUPP;
-
-	if (sd->enabled_pads & BIT_ULL(pad)) {
-		dev_dbg(dev, "pad %u already enabled on %s\n",
-			pad, sd->entity.name);
-		return -EALREADY;
-	}
-
-	/* Start streaming when the first pad is enabled. */
-	if (!sd->enabled_pads) {
-		ret = v4l2_subdev_call(sd, video, s_stream, 1);
-		if (ret)
-			return ret;
-	}
-
-	sd->enabled_pads |= BIT_ULL(pad);
-
-	return 0;
-}
-
 int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
 			       u64 streams_mask)
 {
@@ -2189,21 +2159,33 @@ int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
 	bool already_streaming;
 	u64 enabled_streams;
 	u64 found_streams;
+	bool use_s_stream;
 	int ret;
 
 	/* A few basic sanity checks first. */
 	if (pad >= sd->entity.num_pads)
 		return -EINVAL;
 
+	if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
+		return -EOPNOTSUPP;
+
+	/*
+	 * We use a 64-bit bitmask for tracking enabled pads, so only subdevices
+	 * with 64 pads or less can be supported.
+	 */
+	if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
+		return -EOPNOTSUPP;
+
 	if (!streams_mask)
 		return 0;
 
 	/* Fallback on .s_stream() if .enable_streams() isn't available. */
-	if (!v4l2_subdev_has_op(sd, pad, enable_streams))
-		return v4l2_subdev_enable_streams_fallback(sd, pad,
-							   streams_mask);
+	use_s_stream = !v4l2_subdev_has_op(sd, pad, enable_streams);
 
-	state = v4l2_subdev_lock_and_get_active_state(sd);
+	if (!use_s_stream)
+		state = v4l2_subdev_lock_and_get_active_state(sd);
+	else
+		state = NULL;
 
 	/*
 	 * Verify that the requested streams exist and that they are not
@@ -2231,9 +2213,18 @@ int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
 
 	already_streaming = v4l2_subdev_is_streaming(sd);
 
-	/* Call the .enable_streams() operation. */
-	ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
-			       streams_mask);
+	if (!use_s_stream) {
+		/* Call the .enable_streams() operation. */
+		ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
+				       streams_mask);
+	} else {
+		/* Start streaming when the first pad is enabled. */
+		if (!already_streaming)
+			ret = v4l2_subdev_call(sd, video, s_stream, 1);
+		else
+			ret = 0;
+	}
+
 	if (ret) {
 		dev_dbg(dev, "enable streams %u:%#llx failed: %d\n", pad,
 			streams_mask, ret);
@@ -2243,34 +2234,32 @@ int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
 	/* Mark the streams as enabled. */
 	v4l2_subdev_set_streams_enabled(sd, state, pad, streams_mask, true);
 
-	if (!already_streaming)
+	if (!use_s_stream && !already_streaming)
 		v4l2_subdev_enable_privacy_led(sd);
 
 done:
-	v4l2_subdev_unlock_state(state);
+	if (!use_s_stream)
+		v4l2_subdev_unlock_state(state);
 
 	return ret;
 }
 EXPORT_SYMBOL_GPL(v4l2_subdev_enable_streams);
 
-static int v4l2_subdev_disable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
-						u64 streams_mask)
+int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
+				u64 streams_mask)
 {
 	struct device *dev = sd->entity.graph_obj.mdev->dev;
+	struct v4l2_subdev_state *state;
+	u64 enabled_streams;
+	u64 found_streams;
+	bool use_s_stream;
 	int ret;
 
-	/*
-	 * If the subdev doesn't implement pad-based stream enable, fall back
-	 * to the .s_stream() operation.
-	 */
-	if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
-		return -EOPNOTSUPP;
+	/* A few basic sanity checks first. */
+	if (pad >= sd->entity.num_pads)
+		return -EINVAL;
 
-	/*
-	 * .s_stream() means there is no streams support, so only allowed stream
-	 * is the implicit stream 0.
-	 */
-	if (streams_mask != BIT_ULL(0))
+	if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
 		return -EOPNOTSUPP;
 
 	/*
@@ -2280,46 +2269,16 @@ static int v4l2_subdev_disable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
 	if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
 		return -EOPNOTSUPP;
 
-	if (!(sd->enabled_pads & BIT_ULL(pad))) {
-		dev_dbg(dev, "pad %u already disabled on %s\n",
-			pad, sd->entity.name);
-		return -EALREADY;
-	}
-
-	/* Stop streaming when the last streams are disabled. */
-	if (!(sd->enabled_pads & ~BIT_ULL(pad))) {
-		ret = v4l2_subdev_call(sd, video, s_stream, 0);
-		if (ret)
-			return ret;
-	}
-
-	sd->enabled_pads &= ~BIT_ULL(pad);
-
-	return 0;
-}
-
-int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
-				u64 streams_mask)
-{
-	struct device *dev = sd->entity.graph_obj.mdev->dev;
-	struct v4l2_subdev_state *state;
-	u64 enabled_streams;
-	u64 found_streams;
-	int ret;
-
-	/* A few basic sanity checks first. */
-	if (pad >= sd->entity.num_pads)
-		return -EINVAL;
-
 	if (!streams_mask)
 		return 0;
 
 	/* Fallback on .s_stream() if .disable_streams() isn't available. */
-	if (!v4l2_subdev_has_op(sd, pad, disable_streams))
-		return v4l2_subdev_disable_streams_fallback(sd, pad,
-							    streams_mask);
+	use_s_stream = !v4l2_subdev_has_op(sd, pad, disable_streams);
 
-	state = v4l2_subdev_lock_and_get_active_state(sd);
+	if (!use_s_stream)
+		state = v4l2_subdev_lock_and_get_active_state(sd);
+	else
+		state = NULL;
 
 	/*
 	 * Verify that the requested streams exist and that they are not
@@ -2345,9 +2304,19 @@ int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
 
 	dev_dbg(dev, "disable streams %u:%#llx\n", pad, streams_mask);
 
-	/* Call the .disable_streams() operation. */
-	ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
-			       streams_mask);
+	if (!use_s_stream) {
+		/* Call the .disable_streams() operation. */
+		ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
+				       streams_mask);
+	} else {
+		/* Stop streaming when the last streams are disabled. */
+
+		if (!(sd->enabled_pads & ~BIT_ULL(pad)))
+			ret = v4l2_subdev_call(sd, video, s_stream, 0);
+		else
+			ret = 0;
+	}
+
 	if (ret) {
 		dev_dbg(dev, "disable streams %u:%#llx failed: %d\n", pad,
 			streams_mask, ret);
@@ -2357,10 +2326,12 @@ int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
 	v4l2_subdev_set_streams_enabled(sd, state, pad, streams_mask, false);
 
 done:
-	if (!v4l2_subdev_is_streaming(sd))
-		v4l2_subdev_disable_privacy_led(sd);
+	if (!use_s_stream) {
+		if (!v4l2_subdev_is_streaming(sd))
+			v4l2_subdev_disable_privacy_led(sd);
 
-	v4l2_subdev_unlock_state(state);
+		v4l2_subdev_unlock_state(state);
+	}
 
 	return ret;
 }

-- 
2.34.1

Hi Tomi,

On 10/04/24 6:05 pm, Tomi Valkeinen wrote:
> At the moment the v4l2_subdev_enable/disable_streams() functions call
> fallback helpers to handle the case where the subdev only implements
> .s_stream(), and the main function handles the case where the subdev
> implements streams (V4L2_SUBDEV_FL_STREAMS, which implies
> .enable/disable_streams()).
>
> What is missing is support for subdevs which do not implement streams
> support, but do implement .enable/disable_streams(). Example cases of
> these subdevices are single-stream cameras, where using
> .enable/disable_streams() is not required but helps us remove the users
> of the legacy .s_stream(), and subdevices with multiple source pads (but
> single stream per pad), where .enable/disable_streams() allows the
> subdevice to control the enable/disable state per pad.
>
> The two single-streams cases (.s_stream() and .enable/disable_streams())
> are very similar, and with small changes we can change the
> v4l2_subdev_enable/disable_streams() functions to support all three
> cases, without needing separate fallback functions.
>
> A few potentially problematic details, though:

Does this mean the patch needs to be worked upon more ?

I quickly tested the series by applying it locally with my use case of 
IMX283 .enable/disable streams and s_stream as the helper function and 
it seems I am still seeing the same behaviour as before (i.e. not being 
streamed) and have to carry the workaround as mentioned in [1] **NOTE**

[1] 
https://lore.kernel.org/linux-media/20240313070705.91140-1-umang.jain@ideasonboard.com/

>
> - For the single-streams cases we use sd->enabled_pads field, which
>    limits the number of pads for the subdevice to 64. For simplicity I
>    added the check for this limitation to the beginning of the function,
>    and it also applies to the streams case.
>
> - The fallback functions only allowed the target pad to be a source pad.
>    It is not very clear to me why this check was needed, but it was not
>    needed in the streams case. However, I doubt the
>    v4l2_subdev_enable/disable_streams() code has ever been tested with
>    sink pads, so to be on the safe side, I added the same check
>    to the v4l2_subdev_enable/disable_streams() functions.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
>   drivers/media/v4l2-core/v4l2-subdev.c | 187 ++++++++++++++--------------------
>   1 file changed, 79 insertions(+), 108 deletions(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 0d376d72ecc7..4a73886741f9 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -2106,6 +2106,13 @@ static void v4l2_subdev_collect_streams(struct v4l2_subdev *sd,
>   					u64 *found_streams,
>   					u64 *enabled_streams)
>   {
> +	if (!(sd->flags & V4L2_SUBDEV_FL_STREAMS)) {
> +		*found_streams = BIT_ULL(0);
> +		if (sd->enabled_pads & BIT_ULL(pad))
> +			*enabled_streams = BIT_ULL(0);
> +		return;
> +	}
> +
>   	*found_streams = 0;
>   	*enabled_streams = 0;
>   
> @@ -2127,6 +2134,14 @@ static void v4l2_subdev_set_streams_enabled(struct v4l2_subdev *sd,
>   					    u32 pad, u64 streams_mask,
>   					    bool enabled)
>   {
> +	if (!(sd->flags & V4L2_SUBDEV_FL_STREAMS)) {
> +		if (enabled)
> +			sd->enabled_pads |= BIT_ULL(pad);
> +		else
> +			sd->enabled_pads &= ~BIT_ULL(pad);
> +		return;
> +	}
> +
>   	for (unsigned int i = 0; i < state->stream_configs.num_configs; ++i) {
>   		struct v4l2_subdev_stream_config *cfg =
>   			&state->stream_configs.configs[i];
> @@ -2136,51 +2151,6 @@ static void v4l2_subdev_set_streams_enabled(struct v4l2_subdev *sd,
>   	}
>   }
>   
> -static int v4l2_subdev_enable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
> -					       u64 streams_mask)
> -{
> -	struct device *dev = sd->entity.graph_obj.mdev->dev;
> -	int ret;
> -
> -	/*
> -	 * The subdev doesn't implement pad-based stream enable, fall back
> -	 * to the .s_stream() operation.
> -	 */
> -	if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
> -		return -EOPNOTSUPP;
> -
> -	/*
> -	 * .s_stream() means there is no streams support, so only allowed stream
> -	 * is the implicit stream 0.
> -	 */
> -	if (streams_mask != BIT_ULL(0))
> -		return -EOPNOTSUPP;
> -
> -	/*
> -	 * We use a 64-bit bitmask for tracking enabled pads, so only subdevices
> -	 * with 64 pads or less can be supported.
> -	 */
> -	if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
> -		return -EOPNOTSUPP;
> -
> -	if (sd->enabled_pads & BIT_ULL(pad)) {
> -		dev_dbg(dev, "pad %u already enabled on %s\n",
> -			pad, sd->entity.name);
> -		return -EALREADY;
> -	}
> -
> -	/* Start streaming when the first pad is enabled. */
> -	if (!sd->enabled_pads) {
> -		ret = v4l2_subdev_call(sd, video, s_stream, 1);
> -		if (ret)
> -			return ret;
> -	}
> -
> -	sd->enabled_pads |= BIT_ULL(pad);
> -
> -	return 0;
> -}
> -
>   int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
>   			       u64 streams_mask)
>   {
> @@ -2189,21 +2159,33 @@ int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
>   	bool already_streaming;
>   	u64 enabled_streams;
>   	u64 found_streams;
> +	bool use_s_stream;
>   	int ret;
>   
>   	/* A few basic sanity checks first. */
>   	if (pad >= sd->entity.num_pads)
>   		return -EINVAL;
>   
> +	if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
> +		return -EOPNOTSUPP;
> +
> +	/*
> +	 * We use a 64-bit bitmask for tracking enabled pads, so only subdevices
> +	 * with 64 pads or less can be supported.
> +	 */
> +	if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
> +		return -EOPNOTSUPP;
> +
>   	if (!streams_mask)
>   		return 0;
>   
>   	/* Fallback on .s_stream() if .enable_streams() isn't available. */
> -	if (!v4l2_subdev_has_op(sd, pad, enable_streams))
> -		return v4l2_subdev_enable_streams_fallback(sd, pad,
> -							   streams_mask);
> +	use_s_stream = !v4l2_subdev_has_op(sd, pad, enable_streams);
>   
> -	state = v4l2_subdev_lock_and_get_active_state(sd);
> +	if (!use_s_stream)
> +		state = v4l2_subdev_lock_and_get_active_state(sd);
> +	else
> +		state = NULL;
>   
>   	/*
>   	 * Verify that the requested streams exist and that they are not
> @@ -2231,9 +2213,18 @@ int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
>   
>   	already_streaming = v4l2_subdev_is_streaming(sd);
>   
> -	/* Call the .enable_streams() operation. */
> -	ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
> -			       streams_mask);
> +	if (!use_s_stream) {
> +		/* Call the .enable_streams() operation. */
> +		ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
> +				       streams_mask);
> +	} else {
> +		/* Start streaming when the first pad is enabled. */
> +		if (!already_streaming)
> +			ret = v4l2_subdev_call(sd, video, s_stream, 1);
> +		else
> +			ret = 0;
> +	}
> +
>   	if (ret) {
>   		dev_dbg(dev, "enable streams %u:%#llx failed: %d\n", pad,
>   			streams_mask, ret);
> @@ -2243,34 +2234,32 @@ int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
>   	/* Mark the streams as enabled. */
>   	v4l2_subdev_set_streams_enabled(sd, state, pad, streams_mask, true);
>   
> -	if (!already_streaming)
> +	if (!use_s_stream && !already_streaming)
>   		v4l2_subdev_enable_privacy_led(sd);
>   
>   done:
> -	v4l2_subdev_unlock_state(state);
> +	if (!use_s_stream)
> +		v4l2_subdev_unlock_state(state);
>   
>   	return ret;
>   }
>   EXPORT_SYMBOL_GPL(v4l2_subdev_enable_streams);
>   
> -static int v4l2_subdev_disable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
> -						u64 streams_mask)
> +int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
> +				u64 streams_mask)
>   {
>   	struct device *dev = sd->entity.graph_obj.mdev->dev;
> +	struct v4l2_subdev_state *state;
> +	u64 enabled_streams;
> +	u64 found_streams;
> +	bool use_s_stream;
>   	int ret;
>   
> -	/*
> -	 * If the subdev doesn't implement pad-based stream enable, fall back
> -	 * to the .s_stream() operation.
> -	 */
> -	if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
> -		return -EOPNOTSUPP;
> +	/* A few basic sanity checks first. */
> +	if (pad >= sd->entity.num_pads)
> +		return -EINVAL;
>   
> -	/*
> -	 * .s_stream() means there is no streams support, so only allowed stream
> -	 * is the implicit stream 0.
> -	 */
> -	if (streams_mask != BIT_ULL(0))
> +	if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>   		return -EOPNOTSUPP;
>   
>   	/*
> @@ -2280,46 +2269,16 @@ static int v4l2_subdev_disable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
>   	if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
>   		return -EOPNOTSUPP;
>   
> -	if (!(sd->enabled_pads & BIT_ULL(pad))) {
> -		dev_dbg(dev, "pad %u already disabled on %s\n",
> -			pad, sd->entity.name);
> -		return -EALREADY;
> -	}
> -
> -	/* Stop streaming when the last streams are disabled. */
> -	if (!(sd->enabled_pads & ~BIT_ULL(pad))) {
> -		ret = v4l2_subdev_call(sd, video, s_stream, 0);
> -		if (ret)
> -			return ret;
> -	}
> -
> -	sd->enabled_pads &= ~BIT_ULL(pad);
> -
> -	return 0;
> -}
> -
> -int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
> -				u64 streams_mask)
> -{
> -	struct device *dev = sd->entity.graph_obj.mdev->dev;
> -	struct v4l2_subdev_state *state;
> -	u64 enabled_streams;
> -	u64 found_streams;
> -	int ret;
> -
> -	/* A few basic sanity checks first. */
> -	if (pad >= sd->entity.num_pads)
> -		return -EINVAL;
> -
>   	if (!streams_mask)
>   		return 0;
>   
>   	/* Fallback on .s_stream() if .disable_streams() isn't available. */
> -	if (!v4l2_subdev_has_op(sd, pad, disable_streams))
> -		return v4l2_subdev_disable_streams_fallback(sd, pad,
> -							    streams_mask);
> +	use_s_stream = !v4l2_subdev_has_op(sd, pad, disable_streams);
>   
> -	state = v4l2_subdev_lock_and_get_active_state(sd);
> +	if (!use_s_stream)
> +		state = v4l2_subdev_lock_and_get_active_state(sd);
> +	else
> +		state = NULL;
>   
>   	/*
>   	 * Verify that the requested streams exist and that they are not
> @@ -2345,9 +2304,19 @@ int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
>   
>   	dev_dbg(dev, "disable streams %u:%#llx\n", pad, streams_mask);
>   
> -	/* Call the .disable_streams() operation. */
> -	ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
> -			       streams_mask);
> +	if (!use_s_stream) {
> +		/* Call the .disable_streams() operation. */
> +		ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
> +				       streams_mask);
> +	} else {
> +		/* Stop streaming when the last streams are disabled. */
> +
> +		if (!(sd->enabled_pads & ~BIT_ULL(pad)))
> +			ret = v4l2_subdev_call(sd, video, s_stream, 0);
> +		else
> +			ret = 0;
> +	}
> +
>   	if (ret) {
>   		dev_dbg(dev, "disable streams %u:%#llx failed: %d\n", pad,
>   			streams_mask, ret);
> @@ -2357,10 +2326,12 @@ int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
>   	v4l2_subdev_set_streams_enabled(sd, state, pad, streams_mask, false);
>   
>   done:
> -	if (!v4l2_subdev_is_streaming(sd))
> -		v4l2_subdev_disable_privacy_led(sd);
> +	if (!use_s_stream) {
> +		if (!v4l2_subdev_is_streaming(sd))
> +			v4l2_subdev_disable_privacy_led(sd);
>   
> -	v4l2_subdev_unlock_state(state);
> +		v4l2_subdev_unlock_state(state);
> +	}
>   
>   	return ret;
>   }
>

On 11/04/2024 14:02, Umang Jain wrote:
> Hi Tomi,
> 
> On 10/04/24 6:05 pm, Tomi Valkeinen wrote:
>> At the moment the v4l2_subdev_enable/disable_streams() functions call
>> fallback helpers to handle the case where the subdev only implements
>> .s_stream(), and the main function handles the case where the subdev
>> implements streams (V4L2_SUBDEV_FL_STREAMS, which implies
>> .enable/disable_streams()).
>>
>> What is missing is support for subdevs which do not implement streams
>> support, but do implement .enable/disable_streams(). Example cases of
>> these subdevices are single-stream cameras, where using
>> .enable/disable_streams() is not required but helps us remove the users
>> of the legacy .s_stream(), and subdevices with multiple source pads (but
>> single stream per pad), where .enable/disable_streams() allows the
>> subdevice to control the enable/disable state per pad.
>>
>> The two single-streams cases (.s_stream() and .enable/disable_streams())
>> are very similar, and with small changes we can change the
>> v4l2_subdev_enable/disable_streams() functions to support all three
>> cases, without needing separate fallback functions.
>>
>> A few potentially problematic details, though:
> 
> Does this mean the patch needs to be worked upon more ?

I don't see the two issues below as blockers.

> I quickly tested the series by applying it locally with my use case of 
> IMX283 .enable/disable streams and s_stream as the helper function and 
> it seems I am still seeing the same behaviour as before (i.e. not being 
> streamed) and have to carry the workaround as mentioned in [1] **NOTE**

Ok... Then something bugs here, as it is supposed to fix the problem. 
Can you trace the code a bit to see where it goes wrong?

The execution should go to the "if (!(sd->flags & 
V4L2_SUBDEV_FL_STREAMS))" blocks in v4l2_subdev_collect_streams() and 
v4l2_subdev_set_streams_enabled(),

  Tomi

> 
> [1] 
> https://lore.kernel.org/linux-media/20240313070705.91140-1-umang.jain@ideasonboard.com/
> 
>>
>> - For the single-streams cases we use sd->enabled_pads field, which
>>    limits the number of pads for the subdevice to 64. For simplicity I
>>    added the check for this limitation to the beginning of the function,
>>    and it also applies to the streams case.
>>
>> - The fallback functions only allowed the target pad to be a source pad.
>>    It is not very clear to me why this check was needed, but it was not
>>    needed in the streams case. However, I doubt the
>>    v4l2_subdev_enable/disable_streams() code has ever been tested with
>>    sink pads, so to be on the safe side, I added the same check
>>    to the v4l2_subdev_enable/disable_streams() functions.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>> ---
>>   drivers/media/v4l2-core/v4l2-subdev.c | 187 
>> ++++++++++++++--------------------
>>   1 file changed, 79 insertions(+), 108 deletions(-)
>>
>> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c 
>> b/drivers/media/v4l2-core/v4l2-subdev.c
>> index 0d376d72ecc7..4a73886741f9 100644
>> --- a/drivers/media/v4l2-core/v4l2-subdev.c
>> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
>> @@ -2106,6 +2106,13 @@ static void v4l2_subdev_collect_streams(struct 
>> v4l2_subdev *sd,
>>                       u64 *found_streams,
>>                       u64 *enabled_streams)
>>   {
>> +    if (!(sd->flags & V4L2_SUBDEV_FL_STREAMS)) {
>> +        *found_streams = BIT_ULL(0);
>> +        if (sd->enabled_pads & BIT_ULL(pad))
>> +            *enabled_streams = BIT_ULL(0);
>> +        return;
>> +    }
>> +
>>       *found_streams = 0;
>>       *enabled_streams = 0;
>> @@ -2127,6 +2134,14 @@ static void 
>> v4l2_subdev_set_streams_enabled(struct v4l2_subdev *sd,
>>                           u32 pad, u64 streams_mask,
>>                           bool enabled)
>>   {
>> +    if (!(sd->flags & V4L2_SUBDEV_FL_STREAMS)) {
>> +        if (enabled)
>> +            sd->enabled_pads |= BIT_ULL(pad);
>> +        else
>> +            sd->enabled_pads &= ~BIT_ULL(pad);
>> +        return;
>> +    }
>> +
>>       for (unsigned int i = 0; i < state->stream_configs.num_configs; 
>> ++i) {
>>           struct v4l2_subdev_stream_config *cfg =
>>               &state->stream_configs.configs[i];
>> @@ -2136,51 +2151,6 @@ static void 
>> v4l2_subdev_set_streams_enabled(struct v4l2_subdev *sd,
>>       }
>>   }
>> -static int v4l2_subdev_enable_streams_fallback(struct v4l2_subdev 
>> *sd, u32 pad,
>> -                           u64 streams_mask)
>> -{
>> -    struct device *dev = sd->entity.graph_obj.mdev->dev;
>> -    int ret;
>> -
>> -    /*
>> -     * The subdev doesn't implement pad-based stream enable, fall back
>> -     * to the .s_stream() operation.
>> -     */
>> -    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>> -        return -EOPNOTSUPP;
>> -
>> -    /*
>> -     * .s_stream() means there is no streams support, so only allowed 
>> stream
>> -     * is the implicit stream 0.
>> -     */
>> -    if (streams_mask != BIT_ULL(0))
>> -        return -EOPNOTSUPP;
>> -
>> -    /*
>> -     * We use a 64-bit bitmask for tracking enabled pads, so only 
>> subdevices
>> -     * with 64 pads or less can be supported.
>> -     */
>> -    if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
>> -        return -EOPNOTSUPP;
>> -
>> -    if (sd->enabled_pads & BIT_ULL(pad)) {
>> -        dev_dbg(dev, "pad %u already enabled on %s\n",
>> -            pad, sd->entity.name);
>> -        return -EALREADY;
>> -    }
>> -
>> -    /* Start streaming when the first pad is enabled. */
>> -    if (!sd->enabled_pads) {
>> -        ret = v4l2_subdev_call(sd, video, s_stream, 1);
>> -        if (ret)
>> -            return ret;
>> -    }
>> -
>> -    sd->enabled_pads |= BIT_ULL(pad);
>> -
>> -    return 0;
>> -}
>> -
>>   int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
>>                      u64 streams_mask)
>>   {
>> @@ -2189,21 +2159,33 @@ int v4l2_subdev_enable_streams(struct 
>> v4l2_subdev *sd, u32 pad,
>>       bool already_streaming;
>>       u64 enabled_streams;
>>       u64 found_streams;
>> +    bool use_s_stream;
>>       int ret;
>>       /* A few basic sanity checks first. */
>>       if (pad >= sd->entity.num_pads)
>>           return -EINVAL;
>> +    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>> +        return -EOPNOTSUPP;
>> +
>> +    /*
>> +     * We use a 64-bit bitmask for tracking enabled pads, so only 
>> subdevices
>> +     * with 64 pads or less can be supported.
>> +     */
>> +    if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
>> +        return -EOPNOTSUPP;
>> +
>>       if (!streams_mask)
>>           return 0;
>>       /* Fallback on .s_stream() if .enable_streams() isn't available. */
>> -    if (!v4l2_subdev_has_op(sd, pad, enable_streams))
>> -        return v4l2_subdev_enable_streams_fallback(sd, pad,
>> -                               streams_mask);
>> +    use_s_stream = !v4l2_subdev_has_op(sd, pad, enable_streams);
>> -    state = v4l2_subdev_lock_and_get_active_state(sd);
>> +    if (!use_s_stream)
>> +        state = v4l2_subdev_lock_and_get_active_state(sd);
>> +    else
>> +        state = NULL;
>>       /*
>>        * Verify that the requested streams exist and that they are not
>> @@ -2231,9 +2213,18 @@ int v4l2_subdev_enable_streams(struct 
>> v4l2_subdev *sd, u32 pad,
>>       already_streaming = v4l2_subdev_is_streaming(sd);
>> -    /* Call the .enable_streams() operation. */
>> -    ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
>> -                   streams_mask);
>> +    if (!use_s_stream) {
>> +        /* Call the .enable_streams() operation. */
>> +        ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
>> +                       streams_mask);
>> +    } else {
>> +        /* Start streaming when the first pad is enabled. */
>> +        if (!already_streaming)
>> +            ret = v4l2_subdev_call(sd, video, s_stream, 1);
>> +        else
>> +            ret = 0;
>> +    }
>> +
>>       if (ret) {
>>           dev_dbg(dev, "enable streams %u:%#llx failed: %d\n", pad,
>>               streams_mask, ret);
>> @@ -2243,34 +2234,32 @@ int v4l2_subdev_enable_streams(struct 
>> v4l2_subdev *sd, u32 pad,
>>       /* Mark the streams as enabled. */
>>       v4l2_subdev_set_streams_enabled(sd, state, pad, streams_mask, 
>> true);
>> -    if (!already_streaming)
>> +    if (!use_s_stream && !already_streaming)
>>           v4l2_subdev_enable_privacy_led(sd);
>>   done:
>> -    v4l2_subdev_unlock_state(state);
>> +    if (!use_s_stream)
>> +        v4l2_subdev_unlock_state(state);
>>       return ret;
>>   }
>>   EXPORT_SYMBOL_GPL(v4l2_subdev_enable_streams);
>> -static int v4l2_subdev_disable_streams_fallback(struct v4l2_subdev 
>> *sd, u32 pad,
>> -                        u64 streams_mask)
>> +int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
>> +                u64 streams_mask)
>>   {
>>       struct device *dev = sd->entity.graph_obj.mdev->dev;
>> +    struct v4l2_subdev_state *state;
>> +    u64 enabled_streams;
>> +    u64 found_streams;
>> +    bool use_s_stream;
>>       int ret;
>> -    /*
>> -     * If the subdev doesn't implement pad-based stream enable, fall 
>> back
>> -     * to the .s_stream() operation.
>> -     */
>> -    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>> -        return -EOPNOTSUPP;
>> +    /* A few basic sanity checks first. */
>> +    if (pad >= sd->entity.num_pads)
>> +        return -EINVAL;
>> -    /*
>> -     * .s_stream() means there is no streams support, so only allowed 
>> stream
>> -     * is the implicit stream 0.
>> -     */
>> -    if (streams_mask != BIT_ULL(0))
>> +    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>>           return -EOPNOTSUPP;
>>       /*
>> @@ -2280,46 +2269,16 @@ static int 
>> v4l2_subdev_disable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
>>       if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
>>           return -EOPNOTSUPP;
>> -    if (!(sd->enabled_pads & BIT_ULL(pad))) {
>> -        dev_dbg(dev, "pad %u already disabled on %s\n",
>> -            pad, sd->entity.name);
>> -        return -EALREADY;
>> -    }
>> -
>> -    /* Stop streaming when the last streams are disabled. */
>> -    if (!(sd->enabled_pads & ~BIT_ULL(pad))) {
>> -        ret = v4l2_subdev_call(sd, video, s_stream, 0);
>> -        if (ret)
>> -            return ret;
>> -    }
>> -
>> -    sd->enabled_pads &= ~BIT_ULL(pad);
>> -
>> -    return 0;
>> -}
>> -
>> -int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
>> -                u64 streams_mask)
>> -{
>> -    struct device *dev = sd->entity.graph_obj.mdev->dev;
>> -    struct v4l2_subdev_state *state;
>> -    u64 enabled_streams;
>> -    u64 found_streams;
>> -    int ret;
>> -
>> -    /* A few basic sanity checks first. */
>> -    if (pad >= sd->entity.num_pads)
>> -        return -EINVAL;
>> -
>>       if (!streams_mask)
>>           return 0;
>>       /* Fallback on .s_stream() if .disable_streams() isn't 
>> available. */
>> -    if (!v4l2_subdev_has_op(sd, pad, disable_streams))
>> -        return v4l2_subdev_disable_streams_fallback(sd, pad,
>> -                                streams_mask);
>> +    use_s_stream = !v4l2_subdev_has_op(sd, pad, disable_streams);
>> -    state = v4l2_subdev_lock_and_get_active_state(sd);
>> +    if (!use_s_stream)
>> +        state = v4l2_subdev_lock_and_get_active_state(sd);
>> +    else
>> +        state = NULL;
>>       /*
>>        * Verify that the requested streams exist and that they are not
>> @@ -2345,9 +2304,19 @@ int v4l2_subdev_disable_streams(struct 
>> v4l2_subdev *sd, u32 pad,
>>       dev_dbg(dev, "disable streams %u:%#llx\n", pad, streams_mask);
>> -    /* Call the .disable_streams() operation. */
>> -    ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
>> -                   streams_mask);
>> +    if (!use_s_stream) {
>> +        /* Call the .disable_streams() operation. */
>> +        ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
>> +                       streams_mask);
>> +    } else {
>> +        /* Stop streaming when the last streams are disabled. */
>> +
>> +        if (!(sd->enabled_pads & ~BIT_ULL(pad)))
>> +            ret = v4l2_subdev_call(sd, video, s_stream, 0);
>> +        else
>> +            ret = 0;
>> +    }
>> +
>>       if (ret) {
>>           dev_dbg(dev, "disable streams %u:%#llx failed: %d\n", pad,
>>               streams_mask, ret);
>> @@ -2357,10 +2326,12 @@ int v4l2_subdev_disable_streams(struct 
>> v4l2_subdev *sd, u32 pad,
>>       v4l2_subdev_set_streams_enabled(sd, state, pad, streams_mask, 
>> false);
>>   done:
>> -    if (!v4l2_subdev_is_streaming(sd))
>> -        v4l2_subdev_disable_privacy_led(sd);
>> +    if (!use_s_stream) {
>> +        if (!v4l2_subdev_is_streaming(sd))
>> +            v4l2_subdev_disable_privacy_led(sd);
>> -    v4l2_subdev_unlock_state(state);
>> +        v4l2_subdev_unlock_state(state);
>> +    }
>>       return ret;
>>   }
>>
> 

Hi Tomi,

On 11/04/24 4:37 pm, Tomi Valkeinen wrote:
> On 11/04/2024 14:02, Umang Jain wrote:
>> Hi Tomi,
>>
>> On 10/04/24 6:05 pm, Tomi Valkeinen wrote:
>>> At the moment the v4l2_subdev_enable/disable_streams() functions call
>>> fallback helpers to handle the case where the subdev only implements
>>> .s_stream(), and the main function handles the case where the subdev
>>> implements streams (V4L2_SUBDEV_FL_STREAMS, which implies
>>> .enable/disable_streams()).
>>>
>>> What is missing is support for subdevs which do not implement streams
>>> support, but do implement .enable/disable_streams(). Example cases of
>>> these subdevices are single-stream cameras, where using
>>> .enable/disable_streams() is not required but helps us remove the users
>>> of the legacy .s_stream(), and subdevices with multiple source pads 
>>> (but
>>> single stream per pad), where .enable/disable_streams() allows the
>>> subdevice to control the enable/disable state per pad.
>>>
>>> The two single-streams cases (.s_stream() and 
>>> .enable/disable_streams())
>>> are very similar, and with small changes we can change the
>>> v4l2_subdev_enable/disable_streams() functions to support all three
>>> cases, without needing separate fallback functions.
>>>
>>> A few potentially problematic details, though:
>>
>> Does this mean the patch needs to be worked upon more ?
>
> I don't see the two issues below as blockers.
>
>> I quickly tested the series by applying it locally with my use case 
>> of IMX283 .enable/disable streams and s_stream as the helper function 
>> and it seems I am still seeing the same behaviour as before (i.e. not 
>> being streamed) and have to carry the workaround as mentioned in [1] 
>> **NOTE**
>
> Ok... Then something bugs here, as it is supposed to fix the problem. 
> Can you trace the code a bit to see where it goes wrong?
>
> The execution should go to the "if (!(sd->flags & 
> V4L2_SUBDEV_FL_STREAMS))" blocks in v4l2_subdev_collect_streams() and 
> v4l2_subdev_set_streams_enabled(),

The execution is not reaching in v4l2_subdev_collect streams() even, it 
returns at

     if (!streams_mask)
                 return 0;

in v4l2_subdev_enable_streams()

Refer to : https://paste.debian.net/1313760/

My tree is based on v6.8 currently, but the series applies cleanly, so I 
have not introduced any  rebase artifacts. If you think, v6.8 might be 
causing issues, I'll then try to test on RPi 5 with the latest media 
tree perhaps.

>
>  Tomi
>
>>
>> [1] 
>> https://lore.kernel.org/linux-media/20240313070705.91140-1-umang.jain@ideasonboard.com/
>>
>>>
>>> - For the single-streams cases we use sd->enabled_pads field, which
>>>    limits the number of pads for the subdevice to 64. For simplicity I
>>>    added the check for this limitation to the beginning of the 
>>> function,
>>>    and it also applies to the streams case.
>>>
>>> - The fallback functions only allowed the target pad to be a source 
>>> pad.
>>>    It is not very clear to me why this check was needed, but it was not
>>>    needed in the streams case. However, I doubt the
>>>    v4l2_subdev_enable/disable_streams() code has ever been tested with
>>>    sink pads, so to be on the safe side, I added the same check
>>>    to the v4l2_subdev_enable/disable_streams() functions.
>>>
>>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>>> ---
>>>   drivers/media/v4l2-core/v4l2-subdev.c | 187 
>>> ++++++++++++++--------------------
>>>   1 file changed, 79 insertions(+), 108 deletions(-)
>>>
>>> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c 
>>> b/drivers/media/v4l2-core/v4l2-subdev.c
>>> index 0d376d72ecc7..4a73886741f9 100644
>>> --- a/drivers/media/v4l2-core/v4l2-subdev.c
>>> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
>>> @@ -2106,6 +2106,13 @@ static void 
>>> v4l2_subdev_collect_streams(struct v4l2_subdev *sd,
>>>                       u64 *found_streams,
>>>                       u64 *enabled_streams)
>>>   {
>>> +    if (!(sd->flags & V4L2_SUBDEV_FL_STREAMS)) {
>>> +        *found_streams = BIT_ULL(0);
>>> +        if (sd->enabled_pads & BIT_ULL(pad))
>>> +            *enabled_streams = BIT_ULL(0);
>>> +        return;
>>> +    }
>>> +
>>>       *found_streams = 0;
>>>       *enabled_streams = 0;
>>> @@ -2127,6 +2134,14 @@ static void 
>>> v4l2_subdev_set_streams_enabled(struct v4l2_subdev *sd,
>>>                           u32 pad, u64 streams_mask,
>>>                           bool enabled)
>>>   {
>>> +    if (!(sd->flags & V4L2_SUBDEV_FL_STREAMS)) {
>>> +        if (enabled)
>>> +            sd->enabled_pads |= BIT_ULL(pad);
>>> +        else
>>> +            sd->enabled_pads &= ~BIT_ULL(pad);
>>> +        return;
>>> +    }
>>> +
>>>       for (unsigned int i = 0; i < 
>>> state->stream_configs.num_configs; ++i) {
>>>           struct v4l2_subdev_stream_config *cfg =
>>>               &state->stream_configs.configs[i];
>>> @@ -2136,51 +2151,6 @@ static void 
>>> v4l2_subdev_set_streams_enabled(struct v4l2_subdev *sd,
>>>       }
>>>   }
>>> -static int v4l2_subdev_enable_streams_fallback(struct v4l2_subdev 
>>> *sd, u32 pad,
>>> -                           u64 streams_mask)
>>> -{
>>> -    struct device *dev = sd->entity.graph_obj.mdev->dev;
>>> -    int ret;
>>> -
>>> -    /*
>>> -     * The subdev doesn't implement pad-based stream enable, fall back
>>> -     * to the .s_stream() operation.
>>> -     */
>>> -    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>>> -        return -EOPNOTSUPP;
>>> -
>>> -    /*
>>> -     * .s_stream() means there is no streams support, so only 
>>> allowed stream
>>> -     * is the implicit stream 0.
>>> -     */
>>> -    if (streams_mask != BIT_ULL(0))
>>> -        return -EOPNOTSUPP;
>>> -
>>> -    /*
>>> -     * We use a 64-bit bitmask for tracking enabled pads, so only 
>>> subdevices
>>> -     * with 64 pads or less can be supported.
>>> -     */
>>> -    if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
>>> -        return -EOPNOTSUPP;
>>> -
>>> -    if (sd->enabled_pads & BIT_ULL(pad)) {
>>> -        dev_dbg(dev, "pad %u already enabled on %s\n",
>>> -            pad, sd->entity.name);
>>> -        return -EALREADY;
>>> -    }
>>> -
>>> -    /* Start streaming when the first pad is enabled. */
>>> -    if (!sd->enabled_pads) {
>>> -        ret = v4l2_subdev_call(sd, video, s_stream, 1);
>>> -        if (ret)
>>> -            return ret;
>>> -    }
>>> -
>>> -    sd->enabled_pads |= BIT_ULL(pad);
>>> -
>>> -    return 0;
>>> -}
>>> -
>>>   int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad,
>>>                      u64 streams_mask)
>>>   {
>>> @@ -2189,21 +2159,33 @@ int v4l2_subdev_enable_streams(struct 
>>> v4l2_subdev *sd, u32 pad,
>>>       bool already_streaming;
>>>       u64 enabled_streams;
>>>       u64 found_streams;
>>> +    bool use_s_stream;
>>>       int ret;
>>>       /* A few basic sanity checks first. */
>>>       if (pad >= sd->entity.num_pads)
>>>           return -EINVAL;
>>> +    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>>> +        return -EOPNOTSUPP;
>>> +
>>> +    /*
>>> +     * We use a 64-bit bitmask for tracking enabled pads, so only 
>>> subdevices
>>> +     * with 64 pads or less can be supported.
>>> +     */
>>> +    if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
>>> +        return -EOPNOTSUPP;
>>> +
>>>       if (!streams_mask)
>>>           return 0;
>>>       /* Fallback on .s_stream() if .enable_streams() isn't 
>>> available. */
>>> -    if (!v4l2_subdev_has_op(sd, pad, enable_streams))
>>> -        return v4l2_subdev_enable_streams_fallback(sd, pad,
>>> -                               streams_mask);
>>> +    use_s_stream = !v4l2_subdev_has_op(sd, pad, enable_streams);
>>> -    state = v4l2_subdev_lock_and_get_active_state(sd);
>>> +    if (!use_s_stream)
>>> +        state = v4l2_subdev_lock_and_get_active_state(sd);
>>> +    else
>>> +        state = NULL;
>>>       /*
>>>        * Verify that the requested streams exist and that they are not
>>> @@ -2231,9 +2213,18 @@ int v4l2_subdev_enable_streams(struct 
>>> v4l2_subdev *sd, u32 pad,
>>>       already_streaming = v4l2_subdev_is_streaming(sd);
>>> -    /* Call the .enable_streams() operation. */
>>> -    ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
>>> -                   streams_mask);
>>> +    if (!use_s_stream) {
>>> +        /* Call the .enable_streams() operation. */
>>> +        ret = v4l2_subdev_call(sd, pad, enable_streams, state, pad,
>>> +                       streams_mask);
>>> +    } else {
>>> +        /* Start streaming when the first pad is enabled. */
>>> +        if (!already_streaming)
>>> +            ret = v4l2_subdev_call(sd, video, s_stream, 1);
>>> +        else
>>> +            ret = 0;
>>> +    }
>>> +
>>>       if (ret) {
>>>           dev_dbg(dev, "enable streams %u:%#llx failed: %d\n", pad,
>>>               streams_mask, ret);
>>> @@ -2243,34 +2234,32 @@ int v4l2_subdev_enable_streams(struct 
>>> v4l2_subdev *sd, u32 pad,
>>>       /* Mark the streams as enabled. */
>>>       v4l2_subdev_set_streams_enabled(sd, state, pad, streams_mask, 
>>> true);
>>> -    if (!already_streaming)
>>> +    if (!use_s_stream && !already_streaming)
>>>           v4l2_subdev_enable_privacy_led(sd);
>>>   done:
>>> -    v4l2_subdev_unlock_state(state);
>>> +    if (!use_s_stream)
>>> +        v4l2_subdev_unlock_state(state);
>>>       return ret;
>>>   }
>>>   EXPORT_SYMBOL_GPL(v4l2_subdev_enable_streams);
>>> -static int v4l2_subdev_disable_streams_fallback(struct v4l2_subdev 
>>> *sd, u32 pad,
>>> -                        u64 streams_mask)
>>> +int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
>>> +                u64 streams_mask)
>>>   {
>>>       struct device *dev = sd->entity.graph_obj.mdev->dev;
>>> +    struct v4l2_subdev_state *state;
>>> +    u64 enabled_streams;
>>> +    u64 found_streams;
>>> +    bool use_s_stream;
>>>       int ret;
>>> -    /*
>>> -     * If the subdev doesn't implement pad-based stream enable, 
>>> fall back
>>> -     * to the .s_stream() operation.
>>> -     */
>>> -    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>>> -        return -EOPNOTSUPP;
>>> +    /* A few basic sanity checks first. */
>>> +    if (pad >= sd->entity.num_pads)
>>> +        return -EINVAL;
>>> -    /*
>>> -     * .s_stream() means there is no streams support, so only 
>>> allowed stream
>>> -     * is the implicit stream 0.
>>> -     */
>>> -    if (streams_mask != BIT_ULL(0))
>>> +    if (!(sd->entity.pads[pad].flags & MEDIA_PAD_FL_SOURCE))
>>>           return -EOPNOTSUPP;
>>>       /*
>>> @@ -2280,46 +2269,16 @@ static int 
>>> v4l2_subdev_disable_streams_fallback(struct v4l2_subdev *sd, u32 pad,
>>>       if (pad >= sizeof(sd->enabled_pads) * BITS_PER_BYTE)
>>>           return -EOPNOTSUPP;
>>> -    if (!(sd->enabled_pads & BIT_ULL(pad))) {
>>> -        dev_dbg(dev, "pad %u already disabled on %s\n",
>>> -            pad, sd->entity.name);
>>> -        return -EALREADY;
>>> -    }
>>> -
>>> -    /* Stop streaming when the last streams are disabled. */
>>> -    if (!(sd->enabled_pads & ~BIT_ULL(pad))) {
>>> -        ret = v4l2_subdev_call(sd, video, s_stream, 0);
>>> -        if (ret)
>>> -            return ret;
>>> -    }
>>> -
>>> -    sd->enabled_pads &= ~BIT_ULL(pad);
>>> -
>>> -    return 0;
>>> -}
>>> -
>>> -int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad,
>>> -                u64 streams_mask)
>>> -{
>>> -    struct device *dev = sd->entity.graph_obj.mdev->dev;
>>> -    struct v4l2_subdev_state *state;
>>> -    u64 enabled_streams;
>>> -    u64 found_streams;
>>> -    int ret;
>>> -
>>> -    /* A few basic sanity checks first. */
>>> -    if (pad >= sd->entity.num_pads)
>>> -        return -EINVAL;
>>> -
>>>       if (!streams_mask)
>>>           return 0;
>>>       /* Fallback on .s_stream() if .disable_streams() isn't 
>>> available. */
>>> -    if (!v4l2_subdev_has_op(sd, pad, disable_streams))
>>> -        return v4l2_subdev_disable_streams_fallback(sd, pad,
>>> -                                streams_mask);
>>> +    use_s_stream = !v4l2_subdev_has_op(sd, pad, disable_streams);
>>> -    state = v4l2_subdev_lock_and_get_active_state(sd);
>>> +    if (!use_s_stream)
>>> +        state = v4l2_subdev_lock_and_get_active_state(sd);
>>> +    else
>>> +        state = NULL;
>>>       /*
>>>        * Verify that the requested streams exist and that they are not
>>> @@ -2345,9 +2304,19 @@ int v4l2_subdev_disable_streams(struct 
>>> v4l2_subdev *sd, u32 pad,
>>>       dev_dbg(dev, "disable streams %u:%#llx\n", pad, streams_mask);
>>> -    /* Call the .disable_streams() operation. */
>>> -    ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
>>> -                   streams_mask);
>>> +    if (!use_s_stream) {
>>> +        /* Call the .disable_streams() operation. */
>>> +        ret = v4l2_subdev_call(sd, pad, disable_streams, state, pad,
>>> +                       streams_mask);
>>> +    } else {
>>> +        /* Stop streaming when the last streams are disabled. */
>>> +
>>> +        if (!(sd->enabled_pads & ~BIT_ULL(pad)))
>>> +            ret = v4l2_subdev_call(sd, video, s_stream, 0);
>>> +        else
>>> +            ret = 0;
>>> +    }
>>> +
>>>       if (ret) {
>>>           dev_dbg(dev, "disable streams %u:%#llx failed: %d\n", pad,
>>>               streams_mask, ret);
>>> @@ -2357,10 +2326,12 @@ int v4l2_subdev_disable_streams(struct 
>>> v4l2_subdev *sd, u32 pad,
>>>       v4l2_subdev_set_streams_enabled(sd, state, pad, streams_mask, 
>>> false);
>>>   done:
>>> -    if (!v4l2_subdev_is_streaming(sd))
>>> -        v4l2_subdev_disable_privacy_led(sd);
>>> +    if (!use_s_stream) {
>>> +        if (!v4l2_subdev_is_streaming(sd))
>>> +            v4l2_subdev_disable_privacy_led(sd);
>>> -    v4l2_subdev_unlock_state(state);
>>> +        v4l2_subdev_unlock_state(state);
>>> +    }
>>>       return ret;
>>>   }
>>>
>>
>

On 11/04/2024 14:48, Umang Jain wrote:
> Hi Tomi,
> 
> On 11/04/24 4:37 pm, Tomi Valkeinen wrote:
>> On 11/04/2024 14:02, Umang Jain wrote:
>>> Hi Tomi,
>>>
>>> On 10/04/24 6:05 pm, Tomi Valkeinen wrote:
>>>> At the moment the v4l2_subdev_enable/disable_streams() functions call
>>>> fallback helpers to handle the case where the subdev only implements
>>>> .s_stream(), and the main function handles the case where the subdev
>>>> implements streams (V4L2_SUBDEV_FL_STREAMS, which implies
>>>> .enable/disable_streams()).
>>>>
>>>> What is missing is support for subdevs which do not implement streams
>>>> support, but do implement .enable/disable_streams(). Example cases of
>>>> these subdevices are single-stream cameras, where using
>>>> .enable/disable_streams() is not required but helps us remove the users
>>>> of the legacy .s_stream(), and subdevices with multiple source pads 
>>>> (but
>>>> single stream per pad), where .enable/disable_streams() allows the
>>>> subdevice to control the enable/disable state per pad.
>>>>
>>>> The two single-streams cases (.s_stream() and 
>>>> .enable/disable_streams())
>>>> are very similar, and with small changes we can change the
>>>> v4l2_subdev_enable/disable_streams() functions to support all three
>>>> cases, without needing separate fallback functions.
>>>>
>>>> A few potentially problematic details, though:
>>>
>>> Does this mean the patch needs to be worked upon more ?
>>
>> I don't see the two issues below as blockers.
>>
>>> I quickly tested the series by applying it locally with my use case 
>>> of IMX283 .enable/disable streams and s_stream as the helper function 
>>> and it seems I am still seeing the same behaviour as before (i.e. not 
>>> being streamed) and have to carry the workaround as mentioned in [1] 
>>> **NOTE**
>>
>> Ok... Then something bugs here, as it is supposed to fix the problem. 
>> Can you trace the code a bit to see where it goes wrong?
>>
>> The execution should go to the "if (!(sd->flags & 
>> V4L2_SUBDEV_FL_STREAMS))" blocks in v4l2_subdev_collect_streams() and 
>> v4l2_subdev_set_streams_enabled(),
> 
> The execution is not reaching in v4l2_subdev_collect streams() even, it 
> returns at
> 
>      if (!streams_mask)
>                  return 0;
> 
> in v4l2_subdev_enable_streams()
> 
> Refer to : https://paste.debian.net/1313760/
> 
> My tree is based on v6.8 currently, but the series applies cleanly, so I 
> have not introduced any  rebase artifacts. If you think, v6.8 might be 
> causing issues, I'll then try to test on RPi 5 with the latest media 
> tree perhaps.

So who is calling the v4l2_subdev_enable_streams? I presume it comes 
from v4l2_subdev_s_stream_helper(), in other words the sink side in your 
pipeline is using legacy s_stream?

Indeed, that helper still needs work. It needs to detect if there's no 
routing, and use the implicit stream 0. I missed that one.

  Tomi

Hi Tomi

On 11/04/24 5:23 pm, Tomi Valkeinen wrote:
> On 11/04/2024 14:48, Umang Jain wrote:
>> Hi Tomi,
>>
>> On 11/04/24 4:37 pm, Tomi Valkeinen wrote:
>>> On 11/04/2024 14:02, Umang Jain wrote:
>>>> Hi Tomi,
>>>>
>>>> On 10/04/24 6:05 pm, Tomi Valkeinen wrote:
>>>>> At the moment the v4l2_subdev_enable/disable_streams() functions call
>>>>> fallback helpers to handle the case where the subdev only implements
>>>>> .s_stream(), and the main function handles the case where the subdev
>>>>> implements streams (V4L2_SUBDEV_FL_STREAMS, which implies
>>>>> .enable/disable_streams()).
>>>>>
>>>>> What is missing is support for subdevs which do not implement streams
>>>>> support, but do implement .enable/disable_streams(). Example cases of
>>>>> these subdevices are single-stream cameras, where using
>>>>> .enable/disable_streams() is not required but helps us remove the 
>>>>> users
>>>>> of the legacy .s_stream(), and subdevices with multiple source 
>>>>> pads (but
>>>>> single stream per pad), where .enable/disable_streams() allows the
>>>>> subdevice to control the enable/disable state per pad.
>>>>>
>>>>> The two single-streams cases (.s_stream() and 
>>>>> .enable/disable_streams())
>>>>> are very similar, and with small changes we can change the
>>>>> v4l2_subdev_enable/disable_streams() functions to support all three
>>>>> cases, without needing separate fallback functions.
>>>>>
>>>>> A few potentially problematic details, though:
>>>>
>>>> Does this mean the patch needs to be worked upon more ?
>>>
>>> I don't see the two issues below as blockers.
>>>
>>>> I quickly tested the series by applying it locally with my use case 
>>>> of IMX283 .enable/disable streams and s_stream as the helper 
>>>> function and it seems I am still seeing the same behaviour as 
>>>> before (i.e. not being streamed) and have to carry the workaround 
>>>> as mentioned in [1] **NOTE**
>>>
>>> Ok... Then something bugs here, as it is supposed to fix the 
>>> problem. Can you trace the code a bit to see where it goes wrong?
>>>
>>> The execution should go to the "if (!(sd->flags & 
>>> V4L2_SUBDEV_FL_STREAMS))" blocks in v4l2_subdev_collect_streams() 
>>> and v4l2_subdev_set_streams_enabled(),
>>
>> The execution is not reaching in v4l2_subdev_collect streams() even, 
>> it returns at
>>
>>      if (!streams_mask)
>>                  return 0;
>>
>> in v4l2_subdev_enable_streams()
>>
>> Refer to : https://paste.debian.net/1313760/
>>
>> My tree is based on v6.8 currently, but the series applies cleanly, 
>> so I have not introduced any  rebase artifacts. If you think, v6.8 
>> might be causing issues, I'll then try to test on RPi 5 with the 
>> latest media tree perhaps.
>
> So who is calling the v4l2_subdev_enable_streams? I presume it comes 
> from v4l2_subdev_s_stream_helper(), in other words the sink side in 
> your pipeline is using legacy s_stream?

Yes it comes from the helper function

static const struct v4l2_subdev_video_ops imx283_video_ops = {
         .s_stream = v4l2_subdev_s_stream_helper,
};

>
> Indeed, that helper still needs work. It needs to detect if there's no 
> routing, and use the implicit stream 0. I missed that one.

Yes, no routing in the driver.
>
>  Tomi
>