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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <DF1JETBGEUFA.EK2SDN9BJMB6@bootlin.com>
Date: Thu, 18 Dec 2025 19:00:48 +0100
From: "Luca Ceresoli" <luca.ceresoli@...tlin.com>
To: "Louis Chauvet" <louis.chauvet@...tlin.com>, "Haneen Mohammed"
 <hamohammed.sa@...il.com>, "Simona Vetter" <simona@...ll.ch>, "Melissa Wen"
 <melissa.srw@...il.com>, "Maarten Lankhorst"
 <maarten.lankhorst@...ux.intel.com>, "Maxime Ripard" <mripard@...nel.org>,
 "Thomas Zimmermann" <tzimmermann@...e.de>, "David Airlie"
 <airlied@...il.com>, <jose.exposito89@...il.com>, "Jonathan Corbet"
 <corbet@....net>
Cc: <victoria@...tem76.com>, <sebastian.wick@...hat.com>,
 <thomas.petazzoni@...tlin.com>, <dri-devel@...ts.freedesktop.org>,
 <linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>
Subject: Re: [PATCH RESEND v2 15/32] drm/vkms: Introduce configfs for plane
 color range

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@...tlin.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.

Luca

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