Hi, On Fri, Jun 04, 2021 at 07:17:21PM +0200, Werner Sembach wrote: > Add a new general drm property "active bpc" which can be used by graphic drivers > to report the applied bit depth per pixel back to userspace. Just a heads up, we'll need an open source project that has accepted it before merging it. See https://www.kernel.org/doc/html/latest/gpu/drm-uapi.html#open-source-userspace-requirements > While "max bpc" can be used to change the color depth, there was no way to check > which one actually got used. While in theory the driver chooses the best/highest > color depth within the max bpc setting a user might not be fully aware what his > hardware is or isn't capable off. This is meant as a quick way to double check > the setup. > > In the future, automatic color calibration for screens might also depend on this > information available. > > Signed-off-by: Werner Sembach <wse@xxxxxxxxxxxxxxxxxxx> > --- > drivers/gpu/drm/drm_atomic_uapi.c | 2 ++ > drivers/gpu/drm/drm_connector.c | 40 +++++++++++++++++++++++++++++++ > include/drm/drm_connector.h | 15 ++++++++++++ > 3 files changed, 57 insertions(+) > > diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c > index 268bb69c2e2f..7ae4e40936b5 100644 > --- a/drivers/gpu/drm/drm_atomic_uapi.c > +++ b/drivers/gpu/drm/drm_atomic_uapi.c > @@ -873,6 +873,8 @@ drm_atomic_connector_get_property(struct drm_connector *connector, > *val = 0; > } else if (property == connector->max_bpc_property) { > *val = state->max_requested_bpc; > + } else if (property == connector->active_bpc_property) { > + *val = state->active_bpc; > } else if (connector->funcs->atomic_get_property) { > return connector->funcs->atomic_get_property(connector, > state, property, val); > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c > index 7631f76e7f34..5f42a5be5822 100644 > --- a/drivers/gpu/drm/drm_connector.c > +++ b/drivers/gpu/drm/drm_connector.c > @@ -1195,6 +1195,13 @@ static const struct drm_prop_enum_list dp_colorspaces[] = { > * drm_connector_attach_max_bpc_property() to create and attach the > * property to the connector during initialization. > * > + * active bpc: > + * This read-only range property is used by userspace check the bit depth > + * actually applied by the GPU driver after evaluation all hardware ^ display Depending on the system, the display component might have a GPU attached or not, and the GPU might have a display component or not. > + * capabilities and max bpc. Drivers to use the function > + * drm_connector_attach_active_bpc_property() to create and attach the > + * property to the connector during initialization. > + * > * Connectors also have one standardized atomic property: > * > * CRTC_ID: > @@ -2150,6 +2157,39 @@ int drm_connector_attach_max_bpc_property(struct drm_connector *connector, > } > EXPORT_SYMBOL(drm_connector_attach_max_bpc_property); > > +/** > + * drm_connector_attach_active_bpc_property - attach "active bpc" property > + * @connector: connector to attach active bpc property on. > + * @min: The minimum bit depth supported by the connector. > + * @max: The maximum bit depth supported by the connector. > + * > + * This is used to check the applied bit depth on a connector. > + * > + * Returns: > + * Zero on success, negative errno on failure. > + */ > +int drm_connector_attach_active_bpc_property(struct drm_connector *connector, > + int min, int max) > +{ > + struct drm_device *dev = connector->dev; > + struct drm_property *prop; > + > + prop = connector->active_bpc_property; > + if (!prop) { > + prop = drm_property_create_range(dev, 0, "active bpc", min, max); > + if (!prop) > + return -ENOMEM; > + > + connector->active_bpc_property = prop; > + } > + > + drm_object_attach_property(&connector->base, prop, 0); > + connector->state->active_bpc = 0; I guess we want to default to 8? Maxime
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