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[PATCH v8 8/8] media: i2c: ov9282: dynamic flash_duration maximum

Richard Leitner posted 8 patches 3 months ago
There is a newer version of this series
[PATCH v8 8/8] media: i2c: ov9282: dynamic flash_duration maximum
Posted by Richard Leitner 3 months ago 
This patch sets the current exposure time as maximum for the
flash_duration control. As Flash/Strobes which are longer than the
exposure time have no effect.

Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 drivers/media/i2c/ov9282.c | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
index 7aa74feb3ee44..df7beedba0b9e 100644
--- a/drivers/media/i2c/ov9282.c
+++ b/drivers/media/i2c/ov9282.c
@@ -198,6 +198,7 @@ struct ov9282_mode {
  * @exp_ctrl: Pointer to exposure control
  * @again_ctrl: Pointer to analog gain control
  * @pixel_rate: Pointer to pixel rate control
+ * @flash_duration: Pointer to flash duration control
  * @vblank: Vertical blanking in lines
  * @noncontinuous_clock: Selection of CSI2 noncontinuous clock mode
  * @cur_mode: Pointer to current selected sensor mode
@@ -220,6 +221,7 @@ struct ov9282 {
 		struct v4l2_ctrl *again_ctrl;
 	};
 	struct v4l2_ctrl *pixel_rate;
+	struct v4l2_ctrl *flash_duration;
 	u32 vblank;
 	bool noncontinuous_clock;
 	const struct ov9282_mode *cur_mode;
@@ -611,6 +613,15 @@ static int ov9282_update_controls(struct ov9282 *ov9282,
 					mode->vblank_max, 1, mode->vblank);
 }
 
+static u32 ov9282_exposure_to_us(struct ov9282 *ov9282, u32 exposure)
+{
+	/* calculate exposure time in µs */
+	u32 frame_width = ov9282->cur_mode->width + ov9282->hblank_ctrl->val;
+	u32 trow_us = frame_width * 1000000UL / ov9282->pixel_rate->val;
+
+	return exposure * trow_us;
+}
+
 /**
  * ov9282_update_exp_gain() - Set updated exposure and gain
  * @ov9282: pointer to ov9282 device
@@ -622,9 +633,10 @@ static int ov9282_update_controls(struct ov9282 *ov9282,
 static int ov9282_update_exp_gain(struct ov9282 *ov9282, u32 exposure, u32 gain)
 {
 	int ret;
+	u32 exposure_us = ov9282_exposure_to_us(ov9282, exposure);
 
-	dev_dbg(ov9282->dev, "Set exp %u, analog gain %u",
-		exposure, gain);
+	dev_dbg(ov9282->dev, "Set exp %u (~%u us), analog gain %u",
+		exposure, exposure_us, gain);
 
 	ret = ov9282_write_reg(ov9282, OV9282_REG_HOLD, 1, 1);
 	if (ret)
@@ -635,6 +647,12 @@ static int ov9282_update_exp_gain(struct ov9282 *ov9282, u32 exposure, u32 gain)
 		goto error_release_group_hold;
 
 	ret = ov9282_write_reg(ov9282, OV9282_REG_AGAIN, 1, gain);
+	if (ret)
+		goto error_release_group_hold;
+
+	ret = __v4l2_ctrl_modify_range(ov9282->flash_duration,
+				       0, exposure_us, 1,
+				       OV9282_STROBE_FRAME_SPAN_DEFAULT);
 
 error_release_group_hold:
 	ov9282_write_reg(ov9282, OV9282_REG_HOLD, 1, 0);
@@ -1423,6 +1441,7 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
 	const struct ov9282_mode *mode = ov9282->cur_mode;
 	struct v4l2_fwnode_device_properties props;
 	u32 hblank_min;
+	u32 exposure_us;
 	u32 lpfr;
 	int ret;
 
@@ -1495,8 +1514,11 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
 	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops,
 			  V4L2_CID_FLASH_STROBE_OE, 0, 1, 1, 0);
 
-	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
-			  0, 13900, 1, 8);
+	exposure_us = ov9282_exposure_to_us(ov9282, OV9282_EXPOSURE_DEFAULT);
+	ov9282->flash_duration = v4l2_ctrl_new_std(ctrl_hdlr,
+						   &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
+						   0, exposure_us,
+						   1, OV9282_STROBE_FRAME_SPAN_DEFAULT);
 
 	ret = v4l2_fwnode_device_parse(ov9282->dev, &props);
 	if (!ret) {

-- 
2.47.3
Re: [PATCH v8 8/8] media: i2c: ov9282: dynamic flash_duration maximum
Posted by Sakari Ailus 2 months, 4 weeks ago 
On Tue, Nov 04, 2025 at 03:30:59PM +0100, Richard Leitner wrote:
> This patch sets the current exposure time as maximum for the
> flash_duration control. As Flash/Strobes which are longer than the
> exposure time have no effect.
> 
> Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
> ---
>  drivers/media/i2c/ov9282.c | 30 ++++++++++++++++++++++++++----
>  1 file changed, 26 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
> index 7aa74feb3ee44..df7beedba0b9e 100644
> --- a/drivers/media/i2c/ov9282.c
> +++ b/drivers/media/i2c/ov9282.c
> @@ -198,6 +198,7 @@ struct ov9282_mode {
>   * @exp_ctrl: Pointer to exposure control
>   * @again_ctrl: Pointer to analog gain control
>   * @pixel_rate: Pointer to pixel rate control
> + * @flash_duration: Pointer to flash duration control
>   * @vblank: Vertical blanking in lines
>   * @noncontinuous_clock: Selection of CSI2 noncontinuous clock mode
>   * @cur_mode: Pointer to current selected sensor mode
> @@ -220,6 +221,7 @@ struct ov9282 {
>  		struct v4l2_ctrl *again_ctrl;
>  	};
>  	struct v4l2_ctrl *pixel_rate;
> +	struct v4l2_ctrl *flash_duration;
>  	u32 vblank;
>  	bool noncontinuous_clock;
>  	const struct ov9282_mode *cur_mode;
> @@ -611,6 +613,15 @@ static int ov9282_update_controls(struct ov9282 *ov9282,
>  					mode->vblank_max, 1, mode->vblank);
>  }
>  
> +static u32 ov9282_exposure_to_us(struct ov9282 *ov9282, u32 exposure)
> +{
> +	/* calculate exposure time in µs */
> +	u32 frame_width = ov9282->cur_mode->width + ov9282->hblank_ctrl->val;
> +	u32 trow_us = frame_width * 1000000UL / ov9282->pixel_rate->val;

This can overflow.

> +
> +	return exposure * trow_us;
> +}
> +
>  /**
>   * ov9282_update_exp_gain() - Set updated exposure and gain
>   * @ov9282: pointer to ov9282 device
> @@ -622,9 +633,10 @@ static int ov9282_update_controls(struct ov9282 *ov9282,
>  static int ov9282_update_exp_gain(struct ov9282 *ov9282, u32 exposure, u32 gain)
>  {
>  	int ret;
> +	u32 exposure_us = ov9282_exposure_to_us(ov9282, exposure);
>  
> -	dev_dbg(ov9282->dev, "Set exp %u, analog gain %u",
> -		exposure, gain);
> +	dev_dbg(ov9282->dev, "Set exp %u (~%u us), analog gain %u",
> +		exposure, exposure_us, gain);
>  
>  	ret = ov9282_write_reg(ov9282, OV9282_REG_HOLD, 1, 1);
>  	if (ret)
> @@ -635,6 +647,12 @@ static int ov9282_update_exp_gain(struct ov9282 *ov9282, u32 exposure, u32 gain)
>  		goto error_release_group_hold;
>  
>  	ret = ov9282_write_reg(ov9282, OV9282_REG_AGAIN, 1, gain);
> +	if (ret)
> +		goto error_release_group_hold;
> +
> +	ret = __v4l2_ctrl_modify_range(ov9282->flash_duration,
> +				       0, exposure_us, 1,
> +				       OV9282_STROBE_FRAME_SPAN_DEFAULT);
>  
>  error_release_group_hold:
>  	ov9282_write_reg(ov9282, OV9282_REG_HOLD, 1, 0);
> @@ -1423,6 +1441,7 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
>  	const struct ov9282_mode *mode = ov9282->cur_mode;
>  	struct v4l2_fwnode_device_properties props;
>  	u32 hblank_min;
> +	u32 exposure_us;
>  	u32 lpfr;
>  	int ret;
>  
> @@ -1495,8 +1514,11 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
>  	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops,
>  			  V4L2_CID_FLASH_STROBE_OE, 0, 1, 1, 0);
>  
> -	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
> -			  0, 13900, 1, 8);
> +	exposure_us = ov9282_exposure_to_us(ov9282, OV9282_EXPOSURE_DEFAULT);
> +	ov9282->flash_duration = v4l2_ctrl_new_std(ctrl_hdlr,
> +						   &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
> +						   0, exposure_us,
> +						   1, OV9282_STROBE_FRAME_SPAN_DEFAULT);
>  
>  	ret = v4l2_fwnode_device_parse(ov9282->dev, &props);
>  	if (!ret) {
> 

-- 
Kind regards,

Sakari Ailus
Re: [PATCH v8 8/8] media: i2c: ov9282: dynamic flash_duration maximum
Posted by Richard Leitner 2 months, 3 weeks ago 
Hi Sakari,

On Mon, Nov 10, 2025 at 09:56:39AM +0200, Sakari Ailus wrote:
> On Tue, Nov 04, 2025 at 03:30:59PM +0100, Richard Leitner wrote:
> > This patch sets the current exposure time as maximum for the
> > flash_duration control. As Flash/Strobes which are longer than the
> > exposure time have no effect.
> > 
> > Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
> > ---
> >  drivers/media/i2c/ov9282.c | 30 ++++++++++++++++++++++++++----
> >  1 file changed, 26 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
> > index 7aa74feb3ee44..df7beedba0b9e 100644
> > --- a/drivers/media/i2c/ov9282.c
> > +++ b/drivers/media/i2c/ov9282.c
> > @@ -198,6 +198,7 @@ struct ov9282_mode {
> >   * @exp_ctrl: Pointer to exposure control
> >   * @again_ctrl: Pointer to analog gain control
> >   * @pixel_rate: Pointer to pixel rate control
> > + * @flash_duration: Pointer to flash duration control
> >   * @vblank: Vertical blanking in lines
> >   * @noncontinuous_clock: Selection of CSI2 noncontinuous clock mode
> >   * @cur_mode: Pointer to current selected sensor mode
> > @@ -220,6 +221,7 @@ struct ov9282 {
> >  		struct v4l2_ctrl *again_ctrl;
> >  	};
> >  	struct v4l2_ctrl *pixel_rate;
> > +	struct v4l2_ctrl *flash_duration;
> >  	u32 vblank;
> >  	bool noncontinuous_clock;
> >  	const struct ov9282_mode *cur_mode;
> > @@ -611,6 +613,15 @@ static int ov9282_update_controls(struct ov9282 *ov9282,
> >  					mode->vblank_max, 1, mode->vblank);
> >  }
> >  
> > +static u32 ov9282_exposure_to_us(struct ov9282 *ov9282, u32 exposure)
> > +{
> > +	/* calculate exposure time in µs */
> > +	u32 frame_width = ov9282->cur_mode->width + ov9282->hblank_ctrl->val;
> > +	u32 trow_us = frame_width * 1000000UL / ov9282->pixel_rate->val;
> 
> This can overflow.

Good catch. Thank you! I will fix this by dividing the pixel_rate->val
by 1000000UL instead of multiplying frame_width.

> 
> > +
> > +	return exposure * trow_us;
> > +}
> > +
> >  /**
> >   * ov9282_update_exp_gain() - Set updated exposure and gain
> >   * @ov9282: pointer to ov9282 device
> > @@ -622,9 +633,10 @@ static int ov9282_update_controls(struct ov9282 *ov9282,
> >  static int ov9282_update_exp_gain(struct ov9282 *ov9282, u32 exposure, u32 gain)
> >  {
> >  	int ret;
> > +	u32 exposure_us = ov9282_exposure_to_us(ov9282, exposure);
> >  
> > -	dev_dbg(ov9282->dev, "Set exp %u, analog gain %u",
> > -		exposure, gain);
> > +	dev_dbg(ov9282->dev, "Set exp %u (~%u us), analog gain %u",
> > +		exposure, exposure_us, gain);
> >  
> >  	ret = ov9282_write_reg(ov9282, OV9282_REG_HOLD, 1, 1);
> >  	if (ret)
> > @@ -635,6 +647,12 @@ static int ov9282_update_exp_gain(struct ov9282 *ov9282, u32 exposure, u32 gain)
> >  		goto error_release_group_hold;
> >  
> >  	ret = ov9282_write_reg(ov9282, OV9282_REG_AGAIN, 1, gain);
> > +	if (ret)
> > +		goto error_release_group_hold;
> > +
> > +	ret = __v4l2_ctrl_modify_range(ov9282->flash_duration,
> > +				       0, exposure_us, 1,
> > +				       OV9282_STROBE_FRAME_SPAN_DEFAULT);
> >  
> >  error_release_group_hold:
> >  	ov9282_write_reg(ov9282, OV9282_REG_HOLD, 1, 0);
> > @@ -1423,6 +1441,7 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
> >  	const struct ov9282_mode *mode = ov9282->cur_mode;
> >  	struct v4l2_fwnode_device_properties props;
> >  	u32 hblank_min;
> > +	u32 exposure_us;
> >  	u32 lpfr;
> >  	int ret;
> >  
> > @@ -1495,8 +1514,11 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
> >  	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops,
> >  			  V4L2_CID_FLASH_STROBE_OE, 0, 1, 1, 0);
> >  
> > -	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
> > -			  0, 13900, 1, 8);
> > +	exposure_us = ov9282_exposure_to_us(ov9282, OV9282_EXPOSURE_DEFAULT);
> > +	ov9282->flash_duration = v4l2_ctrl_new_std(ctrl_hdlr,
> > +						   &ov9282_ctrl_ops, V4L2_CID_FLASH_DURATION,
> > +						   0, exposure_us,
> > +						   1, OV9282_STROBE_FRAME_SPAN_DEFAULT);
> >  
> >  	ret = v4l2_fwnode_device_parse(ov9282->dev, &props);
> >  	if (!ret) {
> > 
> 
> -- 
> Kind regards,
> 
> Sakari Ailus

regards;rl

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