[PATCH v5 3/4] drm: Document variable refresh properties

[Wentland, Harry]

On 2018-10-12 12:44 p.m., Nicholas Kazlauskas wrote:
> These include the drm_connector 'vrr_capable' and the drm_crtc
> 'vrr_enabled' properties.
> 
> Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
> ---
>  Documentation/gpu/drm-kms.rst   |  7 +++++++
>  drivers/gpu/drm/drm_connector.c | 22 ++++++++++++++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst
> index 4b1501b4835b..8da2a178cf85 100644
> --- a/Documentation/gpu/drm-kms.rst
> +++ b/Documentation/gpu/drm-kms.rst
> @@ -575,6 +575,13 @@ Explicit Fencing Properties
>  .. kernel-doc:: drivers/gpu/drm/drm_atomic_uapi.c
>     :doc: explicit fencing properties
>  
> +
> +Variable Refresh Properties
> +---------------------------
> +
> +.. kernel-doc:: drivers/gpu/drm/drm_connector.c
> +   :doc: Variable refresh properties
> +
>  Existing KMS Properties
>  -----------------------
>  
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index f0deeb7298d0..2a12853ca917 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -1254,6 +1254,28 @@ int drm_mode_create_scaling_mode_property(struct drm_device *dev)
>  }
>  EXPORT_SYMBOL(drm_mode_create_scaling_mode_property);
>  
> +/**
> + * DOC: Variable refresh properties
> + *
> + * Variable refresh rate control is supported via properties on the
> + * &drm_connector and &drm_crtc objects.
> + *
> + * "vrr_capable":
> + *	Optional &drm_connector boolean property that drivers should attach
> + *	with drm_connector_attach_vrr_capable_property() on connectors that
> + *	could support variable refresh rates. Drivers should update the
> + *	property value by calling drm_connector_set_vrr_capable_property().
> + *
> + *	Absence of the property should indicate absence of support.
> + *
> + * "vrr_enabled":
> + *	Default &drm_crtc boolean property that notifies the driver that the
> + *	variable refresh rate adjustment should be enabled for the CRTC.
> + *
> + *	Support for variable refresh rate will depend on the "vrr_capable"
> + *	property exposed on the &drm_connector object.

We probably want to make it clear that this is a content hint. Maybe something like:

 * "vrr_enabled":
 *	Default &drm_crtc boolean property that notifies the driver that the
 *	content on the CRTC is suitable for variable refresh presentation.
 *	The driver will take that as a hint to enable variable refresh rate
 *	if the receiver supports it, i.e. the "vrr_capable" property on the
 *	&drm_connector_object is true.


Harry

> + */
> +
>  /**
>   * drm_connector_attach_vrr_capable_property - creates the
>   * vrr_capable property
>