[PATCH v7 07/11] drm: Add Content protection type property
Ramalingam C
ramalingam.c at intel.com
Thu Jul 4 10:36:05 UTC 2019
On 2019-07-04 at 14:11:59 +0300, Pekka Paalanen wrote:
> On Tue, 7 May 2019 21:57:41 +0530
> Ramalingam C <ramalingam.c at intel.com> wrote:
>
> > This patch adds a DRM ENUM property to the selected connectors.
> > This property is used for mentioning the protected content's type
> > from userspace to kernel HDCP authentication.
> >
> > Type of the stream is decided by the protected content providers.
> > Type 0 content can be rendered on any HDCP protected display wires.
> > But Type 1 content can be rendered only on HDCP2.2 protected paths.
> >
> > So when a userspace sets this property to Type 1 and starts the HDCP
> > enable, kernel will honour it only if HDCP2.2 authentication is through
> > for type 1. Else HDCP enable will be failed.
> >
> > Need ACK for this new conenctor property from userspace consumer.
> >
> > v2:
> > cp_content_type is replaced with content_protection_type [daniel]
> > check at atomic_set_property is removed [Maarten]
> > v3:
> > %s/content_protection_type/hdcp_content_type [Pekka]
> > v4:
> > property is created for the first requested connector and then reused.
> > [Danvet]
> > v5:
> > kernel doc nits addressed [Daniel]
> > Rebased as part of patch reordering.
> >
> > Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
> > Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> > ---
> > drivers/gpu/drm/drm_atomic_uapi.c | 4 ++++
> > drivers/gpu/drm/drm_connector.c | 18 ++++++++++++++++
> > drivers/gpu/drm/drm_hdcp.c | 36 ++++++++++++++++++++++++++++++-
> > drivers/gpu/drm/i915/intel_hdcp.c | 4 +++-
> > include/drm/drm_connector.h | 7 ++++++
> > include/drm/drm_hdcp.h | 2 +-
> > include/drm/drm_mode_config.h | 6 ++++++
> > include/uapi/drm/drm_mode.h | 4 ++++
> > 8 files changed, 78 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> > index 4131e669785a..a85f3ccfe699 100644
> > --- a/drivers/gpu/drm/drm_atomic_uapi.c
> > +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> > @@ -738,6 +738,8 @@ static int drm_atomic_connector_set_property(struct drm_connector *connector,
> > return -EINVAL;
> > }
> > state->content_protection = val;
> > + } else if (property == config->hdcp_content_type_property) {
> > + state->hdcp_content_type = val;
> > } else if (property == connector->colorspace_property) {
> > state->colorspace = val;
> > } else if (property == config->writeback_fb_id_property) {
> > @@ -816,6 +818,8 @@ drm_atomic_connector_get_property(struct drm_connector *connector,
> > *val = state->scaling_mode;
> > } else if (property == config->content_protection_property) {
> > *val = state->content_protection;
> > + } else if (property == config->hdcp_content_type_property) {
> > + *val = state->hdcp_content_type;
> > } else if (property == config->writeback_fb_id_property) {
> > /* Writeback framebuffer is one-shot, write and forget */
> > *val = 0;
> > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> > index 764c7903edf6..de9e06583e8c 100644
> > --- a/drivers/gpu/drm/drm_connector.c
> > +++ b/drivers/gpu/drm/drm_connector.c
>
> Hi,
>
> below I have some comments and questions before I can say whether
> https://gitlab.freedesktop.org/wayland/weston/merge_requests/48
> adheres to this specification.
>
> > @@ -955,6 +955,24 @@ static const struct drm_prop_enum_list hdmi_colorspaces[] = {
> > * 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).
> > + * HDCP Content Type:
> > + * This property is used by the userspace to configure the kernel with
> > + * to be displayed stream's content type. Content Type of a stream is
> > + * decided by the owner of the stream, as HDCP Type0 or HDCP Type1.
> > + *
> > + * The value of the property can be one the below:
> > + * - DRM_MODE_HDCP_CONTENT_TYPE0 = 0
>
> If this doc is meant as the UAPI doc, it needs to use the string names
> for enum property values, not the C language definitions (integers).
kernel documentation for all other properties followed this way. We
could add string associated to the enum state too for this property.
>
> > + * HDCP Type0 streams can be transmitted on a link which is
> > + * encrypted with HDCP 1.4 or HDCP 2.2.
>
> This wording forbids using any future HDCP version for type0.
We could change it to HDCP1.4 and higher version of HDCP.
>
> > + * - DRM_MODE_HDCP_CONTENT_TYPE1 = 1
> > + * HDCP Type1 streams can be transmitted on a link which is
> > + * encrypted only with HDCP 2.2.
>
> This wording forbids using any future HDCP version for type1.
As of now type 1 is only on HDCP2.2 encrypted link, as no higher version is
available. But as similar to Type 0 we could assume that Type 1 will be
supported on higher HDCP versions too and correct the sentence here.
>
> > + *
> > + * Note that the HDCP Content Type property is specific to HDCP 2.2, and
> > + * defaults to type 0. It is only exposed by drivers supporting HDCP 2.2
>
> Not possible with a future HDCP version greater than 2.2?
>
> Is it intended to be possible to add more content types in the future?
Possible. As per HDCP2.2 spec, 8bits are reserved for the content Type.
>
> > + * If content type is changed when content_protection is not UNDESIRED,
> > + * then kernel will disable the HDCP and re-enable with new type in the
> > + * same atomic commit
>
> Ok, very good to mention this.
>
> > *
> > * max bpc:
> > * This range property is used by userspace to limit the bit depth. When
> > diff --git a/drivers/gpu/drm/drm_hdcp.c b/drivers/gpu/drm/drm_hdcp.c
> > index 0da7b3718bad..75402463466b 100644
> > --- a/drivers/gpu/drm/drm_hdcp.c
> > +++ b/drivers/gpu/drm/drm_hdcp.c
> > @@ -342,23 +342,41 @@ static struct drm_prop_enum_list drm_cp_enum_list[] = {
> > };
> > DRM_ENUM_NAME_FN(drm_get_content_protection_name, drm_cp_enum_list)
> >
> > +static struct drm_prop_enum_list drm_hdcp_content_type_enum_list[] = {
> > + { DRM_MODE_HDCP_CONTENT_TYPE0, "HDCP Type0" },
> > + { DRM_MODE_HDCP_CONTENT_TYPE1, "HDCP Type1" },
> > +};
> > +DRM_ENUM_NAME_FN(drm_get_hdcp_content_type_name,
> > + drm_hdcp_content_type_enum_list)
> > +
> > /**
> > * drm_connector_attach_content_protection_property - attach content protection
> > * property
> > *
> > * @connector: connector to attach CP property on.
> > + * @hdcp_content_type: is HDCP Content Type property needed for connector
> > *
> > * This is used to add support for content protection on select connectors.
> > * Content Protection is intentionally vague to allow for different underlying
> > * technologies, however it is most implemented by HDCP.
> > *
> > + * When hdcp_content_type is true enum property called HDCP Content Type is
> > + * created (if it is not already) and attached to the connector.
> > + *
> > + * This property is used for sending the protected content's stream type
> > + * from userspace to kernel on selected connectors. Protected content provider
> > + * will decide their type of their content and declare the same to kernel.
> > + *
> > + * Content type will be used during the HDCP 2.2 authentication.
> > + * Content type will be set to &drm_connector_state.hdcp_content_type.
> > + *
> > * The content protection will be set to &drm_connector_state.content_protection
> > *
> > * Returns:
> > * Zero on success, negative errno on failure.
> > */
> > int drm_connector_attach_content_protection_property(
> > - struct drm_connector *connector)
> > + struct drm_connector *connector, bool hdcp_content_type)
> > {
> > struct drm_device *dev = connector->dev;
> > struct drm_property *prop =
> > @@ -375,6 +393,22 @@ int drm_connector_attach_content_protection_property(
> > DRM_MODE_CONTENT_PROTECTION_UNDESIRED);
> > dev->mode_config.content_protection_property = prop;
> >
> > + if (!hdcp_content_type)
> > + return 0;
> > +
> > + prop = dev->mode_config.hdcp_content_type_property;
> > + if (!prop)
> > + prop = drm_property_create_enum(dev, 0, "HDCP Content Type",
> > + drm_hdcp_content_type_enum_list,
> > + ARRAY_SIZE(
> > + drm_hdcp_content_type_enum_list));
> > + if (!prop)
> > + return -ENOMEM;
> > +
> > + drm_object_attach_property(&connector->base, prop,
> > + DRM_MODE_HDCP_CONTENT_TYPE0);
> > + dev->mode_config.hdcp_content_type_property = prop;
> > +
> > return 0;
> > }
> > EXPORT_SYMBOL(drm_connector_attach_content_protection_property);
>
> ...
>
> > diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> > index 83cd1636b9be..8ac03351fdee 100644
> > --- a/include/uapi/drm/drm_mode.h
> > +++ b/include/uapi/drm/drm_mode.h
> > @@ -209,6 +209,10 @@ extern "C" {
> > #define DRM_MODE_CONTENT_PROTECTION_DESIRED 1
> > #define DRM_MODE_CONTENT_PROTECTION_ENABLED 2
> >
> > +/* Content Type classification for HDCP2.2 vs others */
> > +#define DRM_MODE_HDCP_CONTENT_TYPE0 0
> > +#define DRM_MODE_HDCP_CONTENT_TYPE1 1
>
> These should not be in a UAPI header. The C language definitions must
> never be exposed to userspace, or misguided userspace will start using
> them.
>
> Instead, UAPI uses the string names to discover the integers at runtime.
This is done as per the usual practice for any existing enum property.
>
> ***
>
> Questions about the already existing "Content Protection" property:
>
> - What happens if userspace attempts to write "Enabled" into it?
* DRM_MODE_CONTENT_PROTECTION_ENABLED = 2
* Userspace has requested content protection, and the link is
* protected. Only the driver can set the property to this value.
* If userspace attempts to set to ENABLED, kernel will return
* -EINVAL.
line number 936 @ drivers/gpu/drm/drm_connector.c
-Ram
>
> - Where is the UAPI documentation that explains how userspace should be
> using the property? (e.g. telling that you cannot set it to "Enabled")
>
>
> Thanks,
> pq
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