[PATCH v9 4/6] drm/hdcp: update content protection property with uevent

[Pekka Paalanen]

On Mon,  8 Jul 2019 16:51:14 +0530
Ramalingam C <ramalingam.c at intel.com> wrote:

> drm function is defined and exported to update a connector's
> content protection property state and to generate a uevent along
> with it.
> 
> Need ACK for the uevent from userspace consumer.
> 
> v2:
>   Update only when state is different from old one.
> v3:
>   KDoc is added [Daniel]
> v4:
>   KDoc is extended bit more [pekka]
> v5:
>   Uevent usage is documented at kdoc of "Content Protection" also
>   [pekka]
> 
> Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> ---
>  drivers/gpu/drm/drm_connector.c | 17 +++++++++++++----
>  drivers/gpu/drm/drm_hdcp.c      | 34 +++++++++++++++++++++++++++++++++
>  include/drm/drm_hdcp.h          |  2 ++
>  3 files changed, 49 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index 732f6645643d..6de906ef10b3 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -947,10 +947,19 @@ static const struct drm_prop_enum_list hdmi_colorspaces[] = {
>   *	- If the state is DESIRED, kernel should attempt to re-authenticate the
>   *	  link whenever possible. This includes across disable/enable, dpms,
>   *	  hotplug, downstream device changes, link status failures, etc..
> - *	- Userspace is responsible for polling the property to determine when
> - *	  the value transitions from ENABLED to DESIRED. This signifies the link
> - *	  is no longer protected and userspace should take appropriate action
> - *	  (whatever that might be).
> + *	- Kernel sends uevent with the connector id and property id through
> + *	  @drm_hdcp_update_content_protection, upon below kernel triggered
> + *	  scenarios:
> + *		DESIRED -> ENABLED	(authentication success)
> + *		ENABLED -> DESIRED	(termination of authentication)
> + *	- Please note no uevents for userspace triggered property state changes,
> + *	  which can't fail such as
> + *		DESIRED/ENABLED -> UNDESIRED
> + *		UNDESIRED -> DESIRED
> + *	- Userspace is responsible for polling the property or listen to uevents
> + *	  to determine when the value transitions from ENABLED to DESIRED.
> + *	  This signifies the link is no longer protected and userspace should
> + *	  take appropriate action (whatever that might be).

Yes!

This doc is exactly what I hoped to see. Good job.

This is also exactly how
https://gitlab.freedesktop.org/wayland/weston/merge_requests/48 deals
with this in userspace. That MR still has some open issues, but I think
nothing related to the uevent.


Thanks,
pq

>   *
>   * HDCP Content Type:
>   *	This Enum property is used by the userspace to declare the content type
> diff --git a/drivers/gpu/drm/drm_hdcp.c b/drivers/gpu/drm/drm_hdcp.c
> index ce235fd1c844..77433ee3d652 100644
> --- a/drivers/gpu/drm/drm_hdcp.c
> +++ b/drivers/gpu/drm/drm_hdcp.c
> @@ -374,6 +374,10 @@ DRM_ENUM_NAME_FN(drm_get_hdcp_content_type_name,
>   *
>   * The content protection will be set to &drm_connector_state.content_protection
>   *
> + * When kernel triggered content protection state change like DESIRED->ENABLED
> + * and ENABLED->DESIRED, will use drm_hdcp_update_content_protection() to update
> + * the content protection state of a connector.
> + *
>   * Returns:
>   * Zero on success, negative errno on failure.
>   */
> @@ -414,3 +418,33 @@ int drm_connector_attach_content_protection_property(
>  	return 0;
>  }
>  EXPORT_SYMBOL(drm_connector_attach_content_protection_property);
> +
> +/**
> + * drm_hdcp_update_content_protection - Updates the content protection state
> + * of a connector
> + *
> + * @connector: drm_connector on which content protection state needs an update
> + * @val: New state of the content protection property
> + *
> + * This function can be used by display drivers, to update the kernel triggered
> + * content protection state changes of a drm_connector such as DESIRED->ENABLED
> + * and ENABLED->DESIRED. No uevent for DESIRED->UNDESIRED or ENABLED->UNDESIRED,
> + * as userspace is triggering such state change and kernel performs it without
> + * fail.This function update the new state of the property into the connector's
> + * state and generate an uevent to notify the userspace.
> + */
> +void drm_hdcp_update_content_protection(struct drm_connector *connector,
> +					u64 val)
> +{
> +	struct drm_device *dev = connector->dev;
> +	struct drm_connector_state *state = connector->state;
> +
> +	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
> +	if (state->content_protection == val)
> +		return;
> +
> +	state->content_protection = val;
> +	drm_sysfs_connector_status_event(connector,
> +				 dev->mode_config.content_protection_property);
> +}
> +EXPORT_SYMBOL(drm_hdcp_update_content_protection);
> diff --git a/include/drm/drm_hdcp.h b/include/drm/drm_hdcp.h
> index 2970abdfaf12..dd864ac9ce85 100644
> --- a/include/drm/drm_hdcp.h
> +++ b/include/drm/drm_hdcp.h
> @@ -292,4 +292,6 @@ bool drm_hdcp_check_ksvs_revoked(struct drm_device *dev,
>  				 u8 *ksvs, u32 ksv_count);
>  int drm_connector_attach_content_protection_property(
>  		struct drm_connector *connector, bool hdcp_content_type);
> +void drm_hdcp_update_content_protection(struct drm_connector *connector,
> +					u64 val);
>  #endif

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