Messages in this thread | | | Date | Wed, 10 Jan 2024 14:39:36 +0100 | Subject | Re: [PATCH 2/7] drm/uAPI: Add "active color format" drm property as feedback for userspace | From | Werner Sembach <> |
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Hi,
Am 09.01.24 um 19:10 schrieb Andri Yngvason: > From: Werner Sembach <wse@tuxedocomputers.com> > > 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> > Signed-off-by: Andri Yngvason <andri@yngvason.is> > Tested-by: Andri Yngvason <andri@yngvason.is>
One suggestion from back then was, instead picking out singular properties like "active color format", to just expose whatever the last HDMI or DP metadata block(s)/frame(s) that was sent over the display wire was to userspace and accompanying it with a parsing script.
Question: Does the driver really actually know what the GPU is ultimatively sending out the wire, or is that decided by a final firmware blob we have no info about?
Greetings
Werner
> --- > drivers/gpu/drm/drm_connector.c | 63 +++++++++++++++++++++++++++++++++ > include/drm/drm_connector.h | 10 ++++++ > 2 files changed, 73 insertions(+) > > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c > index c3725086f4132..30d62e505d188 100644 > --- a/drivers/gpu/drm/drm_connector.c > +++ b/drivers/gpu/drm/drm_connector.c > @@ -1061,6 +1061,14 @@ 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, "not applicable" }, > + { DRM_COLOR_FORMAT_RGB444, "rgb" }, > + { DRM_COLOR_FORMAT_YCBCR444, "ycbcr444" }, > + { DRM_COLOR_FORMAT_YCBCR422, "ycbcr422" }, > + { DRM_COLOR_FORMAT_YCBCR420, "ycbcr420" }, > +}; > + > DRM_ENUM_NAME_FN(drm_get_dp_subconnector_name, > drm_dp_subconnector_enum_list) > > @@ -1390,6 +1398,15 @@ static const u32 dp_colorspaces = > * drm_connector_attach_max_bpc_property() to create and attach the > * property to the connector during initialization. > * > + * 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. Possible values are "not applicable", "rgb", "ycbcr444", > + * "ycbcr422", and "ycbcr420". > + * > * Connectors also have one standardized atomic property: > * > * CRTC_ID: > @@ -2451,6 +2468,52 @@ int drm_connector_attach_max_bpc_property(struct drm_connector *connector, > } > EXPORT_SYMBOL(drm_connector_attach_max_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 fe88d7fc6b8f4..9ae73cfdceeb1 100644 > --- a/include/drm/drm_connector.h > +++ b/include/drm/drm_connector.h > @@ -1699,6 +1699,12 @@ struct drm_connector { > */ > struct drm_property *privacy_screen_hw_state_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) > @@ -2053,6 +2059,10 @@ void drm_connector_attach_privacy_screen_provider( > struct drm_connector *connector, struct drm_privacy_screen *priv); > void drm_connector_update_privacy_screen(const struct drm_connector_state *connector_state); > > +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 > * @refcount: reference count
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