Re: [PATCH RESEND v2 15/32] drm/vkms: Introduce configfs for plane color range

[Louis Chauvet]

On 12/18/25 19:00, Luca Ceresoli wrote:
> On Wed Oct 29, 2025 at 3:36 PM CET, Louis Chauvet wrote:
> > To allows the userspace to test many hardware configuration, introduce a
> > new interface to configure the available color ranges per planes. VKMS
> > supports multiple color ranges, so the userspace can choose any
> > combination.
> >
> > The supported color ranges are configured by writing a color range bitmask
> > to the file `supported_color_ranges` and the default color range is
> > chosen by writing a color encoding bitmask to `default_color_range`.
> >
> > Signed-off-by: Louis Chauvet <louis.chauvet@xxxxxxxxxxx>
>
> > diff --git a/drivers/gpu/drm/vkms/vkms_configfs.c b/drivers/gpu/drm/vkms/vkms_configfs.c
> > index ee2e8d141f9e..3f658dd41272 100644
> > --- a/drivers/gpu/drm/vkms/vkms_configfs.c
> > +++ b/drivers/gpu/drm/vkms/vkms_configfs.c
> > @@ -439,6 +439,91 @@ static ssize_t plane_default_rotation_store(struct config_item *item,
> >   	return count;
> >   }
> >
> > +static ssize_t plane_supported_color_ranges_show(struct config_item *item, char *page)
> > +{
> > +	struct vkms_configfs_plane *plane;
> > +	unsigned int supported_color_range;
>                       supported_color_ranges
>
> > +
> > +	plane = plane_item_to_vkms_configfs_plane(item);
>
> As for previous patches, set this on declaration for consistency (same below).
>
> > +static ssize_t plane_supported_color_ranges_store(struct config_item *item,
> > +						  const char *page, size_t count)
> > +{
> > +	struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
> > +	int ret, val = 0;
> > +
> > +	ret = kstrtouint(page, 10, &val);
> > +	if (ret)
> > +		return ret;
> > +
> > +	/* Should be a supported value */
> > +	if (val & ~(BIT(DRM_COLOR_YCBCR_LIMITED_RANGE) |
> > +		    BIT(DRM_COLOR_YCBCR_FULL_RANGE)))
> > +		return -EINVAL;
> > +	/* Should at least provide one color range */
> > +	if ((val & (BIT(DRM_COLOR_YCBCR_LIMITED_RANGE) |
> > +		    BIT(DRM_COLOR_YCBCR_FULL_RANGE))) == 0)
> > +		return -EINVAL;
> > +
> > +	scoped_guard(mutex, &plane->dev->lock) {
> > +		/* Ensures that the default rotation is included in supported rotation */
>
> Oh no, that comment again! :-)
>
> > +static ssize_t plane_default_color_range_store(struct config_item *item,
> > +					       const char *page, size_t count)
> > +{
> > +	struct vkms_configfs_plane *plane = plane_item_to_vkms_configfs_plane(item);
> > +	int ret, val = 0;
> > +
> > +	ret = kstrtouint(page, 10, &val);
> > +	if (ret)
> > +		return ret;
> > +
> > +	/* Should be a supported value */
> > +	if (val & ~(BIT(DRM_COLOR_YCBCR_LIMITED_RANGE) |
> > +		    BIT(DRM_COLOR_YCBCR_FULL_RANGE)))
> > +		return -EINVAL;
> > +	/* Should at least provide one color range */
> > +	if ((val & (BIT(DRM_COLOR_YCBCR_LIMITED_RANGE) |
> > +		    BIT(DRM_COLOR_YCBCR_FULL_RANGE))) == 0)
> > +		return -EINVAL;
>
> As in patch 12, replace this with is_power_of_2() to check that exactly one
> bit is set.

And as the previous patch, this code is simply wrong...
I shoud check if val is one of DRM_COLOR_YCBCR_LIMITED_RANGE / 
DRM_COLOR_YCBCR_FULL_RANGE

Thanks

> Luca
>
> --
> Luca Ceresoli, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com