Re: [PATCH 3/3] ipu3-cio2: Only allow setting valid mbus codes

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Laurent,

On Fri, Oct 09, 2020 at 03:49:49AM +0300, Laurent Pinchart wrote:
> Hi Sakari,
> 
> Thank you for the patch.
> 
> On Thu, Oct 08, 2020 at 11:47:47PM +0300, Sakari Ailus wrote:
> > Check the mbus code provided by the user is one of those the driver
> > supports. Ignore the code in set_fmt otherwise.
> 
> You're reading my mind :-)
> 
> The code shouldn't be ignored though, when an unsupported code is set,
> it's best to use a fixed default code instead to make the driver
> behaviour as stateless as possible.

I can change it to that, yes.

> 
> > Fixes: c2a6a07afe4a ("media: intel-ipu3: cio2: add new MIPI-CSI2 driver")
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > ---
> >  drivers/media/pci/intel/ipu3/ipu3-cio2.c | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/pci/intel/ipu3/ipu3-cio2.c b/drivers/media/pci/intel/ipu3/ipu3-cio2.c
> > index 9c7b527a8800..2ea6313e00b0 100644
> > --- a/drivers/media/pci/intel/ipu3/ipu3-cio2.c
> > +++ b/drivers/media/pci/intel/ipu3/ipu3-cio2.c
> > @@ -1270,10 +1270,17 @@ static int cio2_subdev_set_fmt(struct v4l2_subdev *sd,
> >  	if (fmt->which == V4L2_SUBDEV_FORMAT_TRY) {
> >  		*v4l2_subdev_get_try_format(sd, cfg, fmt->pad) = fmt->format;
> >  	} else {
> > +		unsigned int i;
> > +
> >  		/* It's the sink, allow changing frame size */
> >  		q->subdev_fmt.width = fmt->format.width;
> >  		q->subdev_fmt.height = fmt->format.height;
> > -		q->subdev_fmt.code = fmt->format.code;
> > +		for (i = 0; i < ARRAY_SIZE(formats); i++) {
> > +			if (formats[i].mbus_code == fmt->format.code) {
> > +				q->subdev_fmt.code = fmt->format.code;
> > +				break;
> > +			}
> > +		}
> >  		fmt->format = q->subdev_fmt;
> 
> This should equally apply to the TRY format, we should accept an
> unsupported code. I'd rework the code as follows:
> 
> 	v4l2_mbus_framefmt *format;
> 
> 	if (fmt->which == V4L2_SUBDEV_FORMAT_TRY)
> 		format = v4l2_subdev_get_try_format(sd, cfg, fmt->pad);
> 	else
> 		format = &q->subdev_fmt;
> 
> (this can be done outside of the mutex-protected section) and then
> operate on format unconditionally.

Agreed.

> Note that we should also allow changing the field and colorspace
> information.

Indeed.

-- 
Sakari Ailus