Re: [PATCH v5 04/10] media: imx219: Make control handler ops for PIXEL_RATE NULL

[Jacopo Mondi <jacopo.mondi@ideasonboard.com>]

Hi Laurent
  sorry if I reply in place of Sakari but I got this fresh

On Mon, Jun 08, 2026 at 10:36:53AM +0300, Laurent Pinchart wrote:
> On Mon, Jun 08, 2026 at 12:53:50AM +0300, Sakari Ailus wrote:
> > The PIXEL_RATE control exists to convey the value to the userspace and has
> > no configuration that would need to be programmed to the sensor. Make the
> > control handler ops for the PIXEL_RATE control NULL and avoid a warning
> > (as well as returning an error) from the driver.
>
> I thought the standard way to handle pixel rate being read only was to
> set the V4L2_CTRL_FLAG_READ_ONLY flag, like we do for e.g.
> V4L2_CID_LINK_FREQ. Is that not correct ?

PIXEL_RATE is RO by default

drivers/media/v4l2-core/v4l2-ctrls-defs.c:      case V4L2_CID_PIXEL_RATE:
drivers/media/v4l2-core/v4l2-ctrls-defs.c-              *type = V4L2_CTRL_TYPE_INTEGER64;
drivers/media/v4l2-core/v4l2-ctrls-defs.c-              *flags |= V4L2_CTRL_FLAG_READ_ONLY;
drivers/media/v4l2-core/v4l2-ctrls-defs.c-              break;

The purpose of setting the ctrl_ops member to NULL is to avoid having
to handle RO controls in the driver implementation of .s_ctrl().

>
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > ---
> >  drivers/media/i2c/imx219.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
> > index e681f80f9e3e..86683fe8a79e 100644
> > --- a/drivers/media/i2c/imx219.c
> > +++ b/drivers/media/i2c/imx219.c
> > @@ -556,7 +556,7 @@ static int imx219_init_controls(struct imx219 *imx219)
> >  		return ret;
> >
> >  	/* By default, PIXEL_RATE is read only */
> > -	imx219->pixel_rate = v4l2_ctrl_new_std(ctrl_hdlr, &imx219_ctrl_ops,
> > +	imx219->pixel_rate = v4l2_ctrl_new_std(ctrl_hdlr, NULL,
> >  					       V4L2_CID_PIXEL_RATE,
> >  					       imx219_get_pixel_rate(imx219),
> >  					       imx219_get_pixel_rate(imx219), 1,
>
> --
> Regards,
>
> Laurent Pinchart
>