| 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
| ||
|
Message-ID: <CADnq5_M5qryDL0thczE1YKBEQc2JToAkh_zr=TphB6YwPwYfgQ@mail.gmail.com>
Date: Thu, 13 Nov 2025 08:49:10 -0500
From: Alex Deucher <alexdeucher@...il.com>
To: Mario Limonciello <mario.limonciello@....com>
Cc: Simona Vetter <simona@...ll.ch>, Alex Deucher <alexander.deucher@....com>,
Christian König <christian.koenig@....com>,
David Airlie <airlied@...il.com>,
"open list:RADEON and AMDGPU DRM DRIVERS" <amd-gfx@...ts.freedesktop.org>,
"open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>, open list <linux-kernel@...r.kernel.org>,
Simona Vetter <simona.vetter@...ll.ch>, Harry Wentland <Harry.Wentland@....com>
Subject: Re: [PATCH] drm/amd: Move adaptive backlight modulation property to
drm core
On Wed, Nov 12, 2025 at 5:27 PM Mario Limonciello
<mario.limonciello@....com> wrote:
>
> The adaptive backlight modulation property is supported on AMD hardware but
> compositors should be aware of it in standard DRM property documentation.
>
> Move the helper to create the property and documentation into DRM.
>
> Suggested-by: Simona Vetter <simona.vetter@...ll.ch>
> Reviewed-by: Harry Wentland <Harry.Wentland@....com>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
Acked-by: Alex Deucher <alexander.deucher@....com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 69 +++------------------
> drivers/gpu/drm/amd/amdgpu/amdgpu_display.h | 7 ---
> drivers/gpu/drm/drm_connector.c | 63 +++++++++++++++++++
> include/drm/drm_connector.h | 8 +++
> 4 files changed, 80 insertions(+), 67 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> index f8b35c487b6c..3d840bef77bf 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
> @@ -1363,67 +1363,9 @@ static const struct drm_prop_enum_list amdgpu_dither_enum_list[] = {
> { AMDGPU_FMT_DITHER_ENABLE, "on" },
> };
>
> -/**
> - * DOC: property for adaptive backlight modulation
> - *
> - * The 'adaptive backlight modulation' property is used for the compositor to
> - * directly control the adaptive backlight modulation power savings feature
> - * that is part of DCN hardware.
> - *
> - * The property will be attached specifically to eDP panels that support it.
> - *
> - * The property is by default set to 'sysfs' to allow the sysfs file 'panel_power_savings'
> - * to be able to control it.
> - * If set to 'off' the compositor will ensure it stays off.
> - * The other values 'min', 'bias min', 'bias max', and 'max' will control the
> - * intensity of the power savings.
> - *
> - * Modifying this value can have implications on color accuracy, so tread
> - * carefully.
> - */
> -static int amdgpu_display_setup_abm_prop(struct amdgpu_device *adev)
> -{
> - const struct drm_prop_enum_list props[] = {
> - { ABM_SYSFS_CONTROL, "sysfs" },
> - { ABM_LEVEL_OFF, "off" },
> - { ABM_LEVEL_MIN, "min" },
> - { ABM_LEVEL_BIAS_MIN, "bias min" },
> - { ABM_LEVEL_BIAS_MAX, "bias max" },
> - { ABM_LEVEL_MAX, "max" },
> - };
> - struct drm_property *prop;
> - int i;
> -
> - if (!adev->dc_enabled)
> - return 0;
> -
> - prop = drm_property_create(adev_to_drm(adev), DRM_MODE_PROP_ENUM,
> - "adaptive backlight modulation",
> - 6);
> - if (!prop)
> - return -ENOMEM;
> -
> - for (i = 0; i < ARRAY_SIZE(props); i++) {
> - int ret;
> -
> - ret = drm_property_add_enum(prop, props[i].type,
> - props[i].name);
> -
> - if (ret) {
> - drm_property_destroy(adev_to_drm(adev), prop);
> -
> - return ret;
> - }
> - }
> -
> - adev->mode_info.abm_level_property = prop;
> -
> - return 0;
> -}
> -
> int amdgpu_display_modeset_create_props(struct amdgpu_device *adev)
> {
> - int sz;
> + int ret, sz;
>
> adev->mode_info.coherent_mode_property =
> drm_property_create_range(adev_to_drm(adev), 0, "coherent", 0, 1);
> @@ -1467,7 +1409,14 @@ int amdgpu_display_modeset_create_props(struct amdgpu_device *adev)
> "dither",
> amdgpu_dither_enum_list, sz);
>
> - return amdgpu_display_setup_abm_prop(adev);
> + adev->mode_info.abm_level_property = drm_create_abm_property(adev_to_drm(adev));
> + if (IS_ERR(adev->mode_info.abm_level_property)) {
> + ret = PTR_ERR(adev->mode_info.abm_level_property);
> + adev->mode_info.abm_level_property = NULL;
> + return ret;
> + }
> +
> + return 0;
> }
>
> void amdgpu_display_update_priority(struct amdgpu_device *adev)
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.h
> index 2b1536a16752..dfa0d642ac16 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.h
> @@ -54,11 +54,4 @@ int amdgpu_display_resume_helper(struct amdgpu_device *adev);
> int amdgpu_display_get_scanout_buffer(struct drm_plane *plane,
> struct drm_scanout_buffer *sb);
>
> -#define ABM_SYSFS_CONTROL -1
> -#define ABM_LEVEL_OFF 0
> -#define ABM_LEVEL_MIN 1
> -#define ABM_LEVEL_BIAS_MIN 2
> -#define ABM_LEVEL_BIAS_MAX 3
> -#define ABM_LEVEL_MAX 4
> -
> #endif
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index 272d6254ea47..376169dac247 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -2603,6 +2603,69 @@ static int drm_mode_create_colorspace_property(struct drm_connector *connector,
> return 0;
> }
>
> +/**
> + * DOC: integrated panel properties
> + *
> + * adaptive backlight modulation:
> + * Adaptive backlight modulation (ABM) is a power savings feature that
> + * dynamically adjusts the backlight brightness based on the content
> + * displayed on the screen. By reducing the backlight brightness for
> + * darker images and increasing it for brighter images, ABM helps to
> + * conserve energy and extend battery life on devices with integrated
> + * displays. This feature is part of AMD DCN hardware.
> + *
> + * sysfs
> + * The ABM property is exposed to userspace via sysfs interface
> + * located at 'amdgpu/panel_power_savings' under the DRM device.
> + * off
> + * Adaptive backlight modulation is disabled.
> + * min
> + * Adaptive backlight modulation is enabled at minimum intensity.
> + * bias min
> + * Adaptive backlight modulation is enabled at a more intense
> + * level than 'min'.
> + * bias max
> + * Adaptive backlight modulation is enabled at a more intense
> + * level than 'bias min'.
> + * max
> + * Adaptive backlight modulation is enabled at maximum intensity.
> + */
> +struct drm_property *drm_create_abm_property(struct drm_device *dev)
> +{
> + const struct drm_prop_enum_list props[] = {
> + { ABM_SYSFS_CONTROL, "sysfs" },
> + { ABM_LEVEL_OFF, "off" },
> + { ABM_LEVEL_MIN, "min" },
> + { ABM_LEVEL_BIAS_MIN, "bias min" },
> + { ABM_LEVEL_BIAS_MAX, "bias max" },
> + { ABM_LEVEL_MAX, "max" },
> + };
> + struct drm_property *prop;
> + int i;
> +
> + prop = drm_property_create(dev, DRM_MODE_PROP_ENUM,
> + "adaptive backlight modulation",
> + 6);
> + if (!prop)
> + return ERR_PTR(-ENOMEM);
> +
> + for (i = 0; i < ARRAY_SIZE(props); i++) {
> + int ret;
> +
> + ret = drm_property_add_enum(prop, props[i].type,
> + props[i].name);
> +
> + if (ret) {
> + drm_property_destroy(dev, prop);
> +
> + return ERR_PTR(ret);
> + }
> + }
> +
> + return prop;
> +}
> +EXPORT_SYMBOL(drm_create_abm_property);
> +
> /**
> * drm_mode_create_hdmi_colorspace_property - create hdmi colorspace property
> * @connector: connector to create the Colorspace property on.
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 8f34f4b8183d..644c0d49500f 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -2454,6 +2454,7 @@ int drm_connector_attach_hdr_output_metadata_property(struct drm_connector *conn
> bool drm_connector_atomic_hdr_metadata_equal(struct drm_connector_state *old_state,
> struct drm_connector_state *new_state);
> int drm_mode_create_aspect_ratio_property(struct drm_device *dev);
> +struct drm_property *drm_create_abm_property(struct drm_device *dev);
> int drm_mode_create_hdmi_colorspace_property(struct drm_connector *connector,
> u32 supported_colorspaces);
> int drm_mode_create_dp_colorspace_property(struct drm_connector *connector,
> @@ -2563,4 +2564,11 @@ const char *drm_get_colorspace_name(enum drm_colorspace colorspace);
> drm_for_each_encoder_mask(encoder, (connector)->dev, \
> (connector)->possible_encoders)
>
> +#define ABM_SYSFS_CONTROL -1
> +#define ABM_LEVEL_OFF 0
> +#define ABM_LEVEL_MIN 1
> +#define ABM_LEVEL_BIAS_MIN 2
> +#define ABM_LEVEL_BIAS_MAX 3
> +#define ABM_LEVEL_MAX 4
> +
> #endif
> --
> 2.51.2
>
Powered by blists - more mailing lists