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

Louis Chauvet
2025-12-19T16:55:20Z

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@bootlin.com>
>
>> 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