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

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Message-ID: <ieqhz2bpvtnej7odzjz3laiudbib3q6j656ed5s7zk4n2nxafh@ci7sdkmdni7d>
Date: Wed, 3 Sep 2025 08:58:04 +0200
From: Richard Leitner <richard.leitner@...ux.dev>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
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 Sakari,

On Mon, Sep 01, 2025 at 11:57:15PM +0300, Sakari Ailus wrote:
> 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.

Sure. Will fix that!

> 
> > +
> > +	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.

It's exactly 100 chars wide, so from a policy point of view it should be
fine ;-). But I'm also fine with breaking it to 80 if you prefer?

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

thanks!

regards;rl