linux-kernel - Re: [PATCH v7 06/10] media: i2c: ov9282: add hardware strobe signal v4l2 control

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Message-ID: <aLYIq6GxLgPM6ReC@kekkonen.localdomain>
Date: Mon, 1 Sep 2025 23:57:15 +0300
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Richard Leitner <richard.leitner@...ux.dev>
Cc: Dave Stevenson <dave.stevenson@...pberrypi.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Lee Jones <lee@...nel.org>, Pavel Machek <pavel@...nel.org>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-leds@...r.kernel.org, Hans Verkuil <hverkuil@...nel.org>
Subject: Re: [PATCH v7 06/10] media: i2c: ov9282: add hardware strobe signal
 v4l2 control

Hi Richard,

On Mon, Sep 01, 2025 at 05:05:11PM +0200, Richard Leitner wrote:
> Add V4L2_CID_FLASH_HW_STROBE_SIGNAL enable/disable support using the
> "strobe output enable" feature of the sensor.
> 
> All values are based on the OV9281 datasheet v1.53 (january 2019) and
> tested using an ov9281 VisionComponents module.
> 
> Signed-off-by: Richard Leitner <richard.leitner@...ux.dev>
> ---
>  drivers/media/i2c/ov9282.c | 25 ++++++++++++++++++++++++-
>  1 file changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
> index f42e0d439753e74d14e3a3592029e48f49234927..ff0f69f0dc3a2d0518806b9ea65c1b520b5c55fb 100644
> --- a/drivers/media/i2c/ov9282.c
> +++ b/drivers/media/i2c/ov9282.c
> @@ -670,6 +670,23 @@ static int ov9282_set_ctrl_vflip(struct ov9282 *ov9282, int value)
>  				current_val);
>  }
>  
> +static int ov9282_set_ctrl_flash_hw_strobe_signal(struct ov9282 *ov9282, bool enable)
> +{
> +	u32 current_val;
> +	int ret = ov9282_read_reg(ov9282, OV9282_REG_OUTPUT_ENABLE6, 1,
> +				  &current_val);
> +	if (ret)
> +		return ret;

Please don't do assignments in variable declaration if that involves error
handling.

> +
> +	if (enable)
> +		current_val |= OV9282_OUTPUT_ENABLE6_STROBE;
> +	else
> +		current_val &= ~OV9282_OUTPUT_ENABLE6_STROBE;
> +
> +	return ov9282_write_reg(ov9282, OV9282_REG_OUTPUT_ENABLE6, 1,
> +				current_val);
> +}
> +
>  /**
>   * ov9282_set_ctrl() - Set subdevice control
>   * @ctrl: pointer to v4l2_ctrl structure
> @@ -736,6 +753,9 @@ static int ov9282_set_ctrl(struct v4l2_ctrl *ctrl)
>  		ret = ov9282_write_reg(ov9282, OV9282_REG_TIMING_HTS, 2,
>  				       (ctrl->val + ov9282->cur_mode->width) >> 1);
>  		break;
> +	case V4L2_CID_FLASH_HW_STROBE_SIGNAL:
> +		ret = ov9282_set_ctrl_flash_hw_strobe_signal(ov9282, ctrl->val);
> +		break;
>  	default:
>  		dev_err(ov9282->dev, "Invalid control %d", ctrl->id);
>  		ret = -EINVAL;
> @@ -1326,7 +1346,7 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
>  	u32 lpfr;
>  	int ret;
>  
> -	ret = v4l2_ctrl_handler_init(ctrl_hdlr, 10);
> +	ret = v4l2_ctrl_handler_init(ctrl_hdlr, 11);
>  	if (ret)
>  		return ret;
>  
> @@ -1391,6 +1411,9 @@ static int ov9282_init_controls(struct ov9282 *ov9282)
>  						OV9282_TIMING_HTS_MAX - mode->width,
>  						1, hblank_min);
>  
> +	/* Flash/Strobe controls */
> +	v4l2_ctrl_new_std(ctrl_hdlr, &ov9282_ctrl_ops, V4L2_CID_FLASH_HW_STROBE_SIGNAL, 0, 1, 1, 0);

This seems rather long.

> +
>  	ret = v4l2_fwnode_device_parse(ov9282->dev, &props);
>  	if (!ret) {
>  		/* Failure sets ctrl_hdlr->error, which we check afterwards anyway */
> 

-- 
Regards,

Sakari Ailus