[v3] media: subdev: Improve stream enable/disable machinery

[PATCH v3 3/9] media: subdev: Add checks for subdev features

Posted by Tomi Valkeinen 1 year, 10 months ago

Add some checks to verify that the subdev driver implements required
features.

A subdevice that supports streams (V4L2_SUBDEV_FL_STREAMS) must do one
of the following:

- Implement neither .enable/disable_streams() nor .s_stream(), if the
  subdev is part of a video driver that uses an internal method to
  enable the subdev.
- Implement only .enable/disable_streams(), if support for legacy
  sink-side subdevices is not needed.
- Implement .enable/disable_streams() and .s_stream(), if support for
  legacy sink-side subdevices is needed.

At the moment the framework doesn't check this requirement. Add the
check.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 4a531c2b16c4..606a909cd778 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -1533,6 +1533,33 @@ int __v4l2_subdev_init_finalize(struct v4l2_subdev *sd, const char *name,
 				struct lock_class_key *key)
 {
 	struct v4l2_subdev_state *state;
+	struct device *dev = sd->dev;
+	bool has_disable_streams;
+	bool has_enable_streams;
+	bool has_s_stream;
+
+	/* Check that the subdevice implements the required features */
+
+	has_s_stream = v4l2_subdev_has_op(sd, video, s_stream);
+	has_enable_streams = v4l2_subdev_has_op(sd, pad, enable_streams);
+	has_disable_streams = v4l2_subdev_has_op(sd, pad, disable_streams);
+
+	if (has_enable_streams != has_disable_streams) {
+		dev_err(dev,
+			"subdev '%s' must implement both or neither of .enable_streams() and .disable_streams()\n",
+			sd->name);
+		return -EINVAL;
+	}
+
+	if (sd->flags & V4L2_SUBDEV_FL_STREAMS) {
+		if (has_s_stream && !has_enable_streams) {
+			dev_err(dev,
+				"subdev '%s' must implement .enable/disable_streams()\n",
+				sd->name);
+
+			return -EINVAL;
+		}
+	}
 
 	state = __v4l2_subdev_state_alloc(sd, name, key);
 	if (IS_ERR(state))

-- 
2.34.1

Re: [PATCH v3 3/9] media: subdev: Add checks for subdev features

Posted by Laurent Pinchart 1 year, 10 months ago

Hi Tomi,

Thank you for the patch.

On Wed, Apr 10, 2024 at 03:35:50PM +0300, Tomi Valkeinen wrote:
> Add some checks to verify that the subdev driver implements required
> features.
> 
> A subdevice that supports streams (V4L2_SUBDEV_FL_STREAMS) must do one
> of the following:
> 
> - Implement neither .enable/disable_streams() nor .s_stream(), if the
>   subdev is part of a video driver that uses an internal method to
>   enable the subdev.
> - Implement only .enable/disable_streams(), if support for legacy
>   sink-side subdevices is not needed.
> - Implement .enable/disable_streams() and .s_stream(), if support for
>   legacy sink-side subdevices is needed.
> 
> At the moment the framework doesn't check this requirement. Add the
> check.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  drivers/media/v4l2-core/v4l2-subdev.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 4a531c2b16c4..606a909cd778 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -1533,6 +1533,33 @@ int __v4l2_subdev_init_finalize(struct v4l2_subdev *sd, const char *name,
>  				struct lock_class_key *key)
>  {
>  	struct v4l2_subdev_state *state;
> +	struct device *dev = sd->dev;
> +	bool has_disable_streams;
> +	bool has_enable_streams;
> +	bool has_s_stream;
> +
> +	/* Check that the subdevice implements the required features */
> +
> +	has_s_stream = v4l2_subdev_has_op(sd, video, s_stream);
> +	has_enable_streams = v4l2_subdev_has_op(sd, pad, enable_streams);
> +	has_disable_streams = v4l2_subdev_has_op(sd, pad, disable_streams);
> +
> +	if (has_enable_streams != has_disable_streams) {
> +		dev_err(dev,
> +			"subdev '%s' must implement both or neither of .enable_streams() and .disable_streams()\n",
> +			sd->name);
> +		return -EINVAL;
> +	}
> +
> +	if (sd->flags & V4L2_SUBDEV_FL_STREAMS) {
> +		if (has_s_stream && !has_enable_streams) {
> +			dev_err(dev,
> +				"subdev '%s' must implement .enable/disable_streams()\n",
> +				sd->name);
> +
> +			return -EINVAL;
> +		}
> +	}
>  
>  	state = __v4l2_subdev_state_alloc(sd, name, key);
>  	if (IS_ERR(state))
> 

-- 
Regards,

Laurent Pinchart

Re: [PATCH v3 3/9] media: subdev: Add checks for subdev features

Posted by Umang Jain 1 year, 10 months ago

Hi Tomi,

On 10/04/24 6:05 pm, Tomi Valkeinen wrote:
> Add some checks to verify that the subdev driver implements required
> features.
>
> A subdevice that supports streams (V4L2_SUBDEV_FL_STREAMS) must do one
> of the following:
>
> - Implement neither .enable/disable_streams() nor .s_stream(), if the
>    subdev is part of a video driver that uses an internal method to
>    enable the subdev.
> - Implement only .enable/disable_streams(), if support for legacy
>    sink-side subdevices is not needed.
> - Implement .enable/disable_streams() and .s_stream(), if support for
>    legacy sink-side subdevices is needed.
>
> At the moment the framework doesn't check this requirement. Add the
> check.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

The code looks aligned with the restrictions mentioned in the commit 
message.

Only one question in case 3), does the .s_stream() needs to be helper 
function I think, can we (or do we) need to check that as well?

Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>

> ---
>   drivers/media/v4l2-core/v4l2-subdev.c | 27 +++++++++++++++++++++++++++
>   1 file changed, 27 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 4a531c2b16c4..606a909cd778 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -1533,6 +1533,33 @@ int __v4l2_subdev_init_finalize(struct v4l2_subdev *sd, const char *name,
>   				struct lock_class_key *key)
>   {
>   	struct v4l2_subdev_state *state;
> +	struct device *dev = sd->dev;
> +	bool has_disable_streams;
> +	bool has_enable_streams;
> +	bool has_s_stream;
> +
> +	/* Check that the subdevice implements the required features */
> +
> +	has_s_stream = v4l2_subdev_has_op(sd, video, s_stream);
> +	has_enable_streams = v4l2_subdev_has_op(sd, pad, enable_streams);
> +	has_disable_streams = v4l2_subdev_has_op(sd, pad, disable_streams);
> +
> +	if (has_enable_streams != has_disable_streams) {
> +		dev_err(dev,
> +			"subdev '%s' must implement both or neither of .enable_streams() and .disable_streams()\n",
> +			sd->name);
> +		return -EINVAL;
> +	}
> +
> +	if (sd->flags & V4L2_SUBDEV_FL_STREAMS) {
> +		if (has_s_stream && !has_enable_streams) {
> +			dev_err(dev,
> +				"subdev '%s' must implement .enable/disable_streams()\n",
> +				sd->name);
> +
> +			return -EINVAL;
> +		}
> +	}
>   
>   	state = __v4l2_subdev_state_alloc(sd, name, key);
>   	if (IS_ERR(state))
>

Re: [PATCH v3 3/9] media: subdev: Add checks for subdev features

Posted by Tomi Valkeinen 1 year, 10 months ago

On 11/04/2024 08:34, Umang Jain wrote:
> Hi Tomi,
> 
> On 10/04/24 6:05 pm, Tomi Valkeinen wrote:
>> Add some checks to verify that the subdev driver implements required
>> features.
>>
>> A subdevice that supports streams (V4L2_SUBDEV_FL_STREAMS) must do one
>> of the following:
>>
>> - Implement neither .enable/disable_streams() nor .s_stream(), if the
>>    subdev is part of a video driver that uses an internal method to
>>    enable the subdev.
>> - Implement only .enable/disable_streams(), if support for legacy
>>    sink-side subdevices is not needed.
>> - Implement .enable/disable_streams() and .s_stream(), if support for
>>    legacy sink-side subdevices is needed.
>>
>> At the moment the framework doesn't check this requirement. Add the
>> check.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> 
> The code looks aligned with the restrictions mentioned in the commit 
> message.
> 
> Only one question in case 3), does the .s_stream() needs to be helper 
> function I think, can we (or do we) need to check that as well?

Do you mean if in case 3, the s_stream should always be set to 
v4l2_subdev_s_stream_helper()?

I don't think so. The helper only works for subdevices with a single 
source pad. And even if the helper worked for multiple source pads, I 
don't see any specific reason to prevent the drivers from having their 
own implementation.

  Tomi

> Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
> 
>> ---
>>   drivers/media/v4l2-core/v4l2-subdev.c | 27 +++++++++++++++++++++++++++
>>   1 file changed, 27 insertions(+)
>>
>> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c 
>> b/drivers/media/v4l2-core/v4l2-subdev.c
>> index 4a531c2b16c4..606a909cd778 100644
>> --- a/drivers/media/v4l2-core/v4l2-subdev.c
>> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
>> @@ -1533,6 +1533,33 @@ int __v4l2_subdev_init_finalize(struct 
>> v4l2_subdev *sd, const char *name,
>>                   struct lock_class_key *key)
>>   {
>>       struct v4l2_subdev_state *state;
>> +    struct device *dev = sd->dev;
>> +    bool has_disable_streams;
>> +    bool has_enable_streams;
>> +    bool has_s_stream;
>> +
>> +    /* Check that the subdevice implements the required features */
>> +
>> +    has_s_stream = v4l2_subdev_has_op(sd, video, s_stream);
>> +    has_enable_streams = v4l2_subdev_has_op(sd, pad, enable_streams);
>> +    has_disable_streams = v4l2_subdev_has_op(sd, pad, disable_streams);
>> +
>> +    if (has_enable_streams != has_disable_streams) {
>> +        dev_err(dev,
>> +            "subdev '%s' must implement both or neither of 
>> .enable_streams() and .disable_streams()\n",
>> +            sd->name);
>> +        return -EINVAL;
>> +    }
>> +
>> +    if (sd->flags & V4L2_SUBDEV_FL_STREAMS) {
>> +        if (has_s_stream && !has_enable_streams) {
>> +            dev_err(dev,
>> +                "subdev '%s' must implement 
>> .enable/disable_streams()\n",
>> +                sd->name);
>> +
>> +            return -EINVAL;
>> +        }
>> +    }
>>       state = __v4l2_subdev_state_alloc(sd, name, key);
>>       if (IS_ERR(state))
>>
>