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SubjectRe: [PATCH v4 06/17] drm/uAPI: Add "active color format" drm property as feedback for userspace
On Fri, 18 Jun 2021 11:11:05 +0200
Werner Sembach <wse@tuxedocomputers.com> wrote:

> Add a new general drm property "active color format" which can be used by
> graphic drivers to report the used color format back to userspace.
>
> There was no way to check which color format got actually used on a given
> monitor. To surely predict this, one must know the exact capabilities of
> the monitor, the GPU, and the connection used and what the default
> behaviour of the used driver is (e.g. amdgpu prefers YCbCr 4:4:4 while i915
> prefers RGB). This property helps eliminating the guessing on this point.
>
> In the future, automatic color calibration for screens might also depend on
> this information being available.
>
> Signed-off-by: Werner Sembach <wse@tuxedocomputers.com>
> ---
> drivers/gpu/drm/drm_connector.c | 61 +++++++++++++++++++++++++++++++++
> include/drm/drm_connector.h | 9 +++++
> 2 files changed, 70 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index 943f6b61053b..684d7abdf0eb 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -889,6 +889,14 @@ static const struct drm_prop_enum_list drm_dp_subconnector_enum_list[] = {
> { DRM_MODE_SUBCONNECTOR_Native, "Native" }, /* DP */
> };
>
> +static const struct drm_prop_enum_list drm_active_color_format_enum_list[] = {
> + { 0, "unknown" },
> + { DRM_COLOR_FORMAT_RGB444, "rgb" },
> + { DRM_COLOR_FORMAT_YCRCB444, "ycbcr444" },
> + { DRM_COLOR_FORMAT_YCRCB422, "ycbcr422" },
> + { DRM_COLOR_FORMAT_YCRCB420, "ycbcr420" },
> +};
> +
> DRM_ENUM_NAME_FN(drm_get_dp_subconnector_name,
> drm_dp_subconnector_enum_list)
>
> @@ -1205,6 +1213,14 @@ static const struct drm_prop_enum_list dp_colorspaces[] = {
> * Drivers shall use drm_connector_attach_active_bpc_property() to install
> * this property.
> *
> + * active color format:
> + * This read-only property tells userspace the color format actually used
> + * by the hardware display engine on "the cable" on a connector. The chosen
> + * value depends on hardware capabilities, both display engine and
> + * connected monitor. Drivers shall use
> + * drm_connector_attach_active_color_format_property() to install this
> + * property.
> + *
> * Connectors also have one standardized atomic property:
> *
> * CRTC_ID:
> @@ -2203,6 +2219,51 @@ void drm_connector_set_active_bpc_property(struct drm_connector *connector, int
> }
> EXPORT_SYMBOL(drm_connector_set_active_bpc_property);
>
> +/**
> + * drm_connector_attach_active_color_format_property - attach "active color format" property
> + * @connector: connector to attach active color format property on.
> + *
> + * This is used to check the applied color format on a connector.
> + *
> + * Returns:
> + * Zero on success, negative errno on failure.
> + */
> +int drm_connector_attach_active_color_format_property(struct drm_connector *connector)
> +{
> + struct drm_device *dev = connector->dev;
> + struct drm_property *prop;
> +
> + if (!connector->active_color_format_property) {
> + prop = drm_property_create_enum(dev, DRM_MODE_PROP_IMMUTABLE, "active color format",
> + drm_active_color_format_enum_list,
> + ARRAY_SIZE(drm_active_color_format_enum_list));
> + if (!prop)
> + return -ENOMEM;
> +
> + connector->active_color_format_property = prop;
> + drm_object_attach_property(&connector->base, prop, 0);
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_connector_attach_active_color_format_property);
> +
> +/**
> + * drm_connector_set_active_color_format_property - sets the active color format property for a
> + * connector
> + * @connector: drm connector
> + * @active_color_format: color format for the connector currently active on "the cable"
> + *
> + * Should be used by atomic drivers to update the active color format over a connector.
> + */
> +void drm_connector_set_active_color_format_property(struct drm_connector *connector,
> + u32 active_color_format)
> +{
> + drm_object_property_set_value(&connector->base, connector->active_color_format_property,
> + active_color_format);
> +}
> +EXPORT_SYMBOL(drm_connector_set_active_color_format_property);
> +
> /**
> * drm_connector_attach_hdr_output_metadata_property - attach "HDR_OUTPUT_METADA" property
> * @connector: connector to attach the property on.
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index eee86de62a5f..8a5197f14e87 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -1386,6 +1386,12 @@ struct drm_connector {
> */
> struct drm_property *active_bpc_property;
>
> + /**
> + * @active_color_format_property: Default connector property for the
> + * active color format to be driven out of the connector.
> + */
> + struct drm_property *active_color_format_property;
> +
> #define DRM_CONNECTOR_POLL_HPD (1 << 0)
> #define DRM_CONNECTOR_POLL_CONNECT (1 << 1)
> #define DRM_CONNECTOR_POLL_DISCONNECT (1 << 2)
> @@ -1710,6 +1716,9 @@ int drm_connector_attach_max_bpc_property(struct drm_connector *connector,
> int min, int max);
> int drm_connector_attach_active_bpc_property(struct drm_connector *connector, int min, int max);
> void drm_connector_set_active_bpc_property(struct drm_connector *connector, int active_bpc);
> +int drm_connector_attach_active_color_format_property(struct drm_connector *connector);
> +void drm_connector_set_active_color_format_property(struct drm_connector *connector,
> + u32 active_color_format);
>
> /**
> * struct drm_tile_group - Tile group metadata

Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>


Thanks,
pq
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