[Intel-gfx] [RFC v3] drm/hdcp: drm enum property for CP State
Sean Paul
seanpaul at chromium.org
Wed Jul 26 14:52:50 UTC 2017
On Wed, Jul 26, 2017 at 03:24:10PM +0530, Ramalingam C wrote:
>
>
> On Tuesday 25 July 2017 06:04 PM, Sean Paul wrote:
> > On Mon, Jul 24, 2017 at 2:12 PM, Ramalingam C <ramalingam.c at intel.com> wrote:
> > > DRM connector property is created to represent the content protection
> > > state of the connector and to configure the same.
> > >
> > > Content protection states defined:
> > > DRM_MODE_CONTENT_PROTECTION_UNSUPPORTED - Unsupported
> > > DRM_MODE_CONTENT_PROTECTION_DISABLE - Disabled
> > > DRM_MODE_CONTENT_PROTECTION_ENABLE - Enabled
> > >
> > > v2: Redesigned the property to match with CP needs of CrOS [Sean].
> > >
> > > v3: Renamed the state names. Header is removed [sean].
> > >
> > > Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
> > > ---
> > > drivers/gpu/drm/drm_connector.c | 14 ++++++++++++++
> > > include/drm/drm_mode_config.h | 5 +++++
> > > include/uapi/drm/drm_mode.h | 5 +++++
> > > 3 files changed, 24 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> > > index 5cd61af..d6aaa08 100644
> > > --- a/drivers/gpu/drm/drm_connector.c
> > > +++ b/drivers/gpu/drm/drm_connector.c
> > > @@ -617,6 +617,13 @@ static const struct drm_prop_enum_list drm_link_status_enum_list[] = {
> > > };
> > > DRM_ENUM_NAME_FN(drm_get_link_status_name, drm_link_status_enum_list)
> > >
> > > +static const struct drm_prop_enum_list drm_cp_enum_list[] = {
> > > + { DRM_MODE_CONTENT_PROTECTION_UNSUPPORTED, "Unsupported" },
> > You're still changing the enum names from the original patch/CrOS
> > implementation.
> >
> > https://lists.freedesktop.org/archives/dri-devel/2014-December/073336.html
> >
> > https://cs.chromium.org/chromium/src/ui/ozone/platform/drm/gpu/drm_display.cc?l=27
>
> Sean,
>
> I think we have bit of confusion here.
Agreed :)
>
> And in previous discussion you were fine with new state of property that is
> "unsupported" - indicates no common HDCP version is supported on HDCP src
> and Sink combo.
>
> when CP is not possible, if property exist, userspace will interpret it as
> CP is supported and attempt for enabling.
> I prefer indicating Unsupported state than failing such requests blindly.
>
> In that case to interpret the new state, we need to change CrOS User space
> code.
>
> In the RFC you mentioned above, two version of uapi interfaces are
> discussed.
> V1 uses single property to configure the CP and also for status
> indication.
> V2 uses two properties one for configuring and another one for
> status of Content protection.
>
> But CrOS user space is currently using the V1 interface.
>
> which will be preferred approach right now (V1/V2)?
> In either way we need to change the CrOS :(
We can't upstream code without a userspace implementation, so V1. Without any
modifications.
As has been mentioned before in this thread, it's a lot easier to upstream code
that is proven to work, than it is to merge speculative API. Further, if this
patch were merged, it would be CrOS which is currently the only consumer... not
a good look :)
>
> Lets say we need to modify CrOS user space, will there be any help for that?
> I am not aware what it takes though.
You could probably reach out to chromium-dev at chromium.org or the author of the
Chrome hdcp implementation for help.
Sean
>
> I am trying to discuss both uapi versions of V1 and V2. I prefer V2 though.
>
> If V1 is preferred we need a single property as below
> "content protection" property with {"Unsupported", "Undesired", "Desired",
> "Enabled"}
> "Type1_desired" and "Type1_Enabled" are needed for
> HDCP2.2
>
>
> If V2 is preferred we need two properties as below
>
> "content protection" property with {"Unsupported", "Undesired", "Desired"}
> ("Type1_desired" - needed For HDCP2.2)
> "content protection status" property with {"Disabled", "Enabled"}
> ("Type1_enabled" - needed for HDCP2.2)
>
> - Not providing the ksv, as reflecting one ksv is not serving any
> purpose.
> Even for revocation check you need provision to list all device
> IDs (Max 32devices x 5Bytes ID) attached to repeater.
> So it is good to reflect the current protection level of link
> through enum.
>
> And Usage will be as below:
> By default property "content protection" will be set to
> - "Unsupported" (If CP is not possible on the Link)
> - "Undesired" (If Link is not protected. CP is possible)
> By default property "content protection status" will be set to
> - "Disabled"
>
> the sequence of enabling protection on a link:
> - User space will set "content protection" "Undesired" -> "Desired"
> - kernel will start the Authentication.
> - Once Auth is successful, kernel will change "content protection
> status" as "Disabled" -> "Enabled"
>
> The sequence of disabling protection on a link:
> - User space will set "content protection" "Desired" -> "Undesired"
> - kernel will start the disable encryption.
> - Once it is successful, kernel will change "content protection
> status" as "Enabled" -> "Disabled"
>
> The sequence in case of encryption Failure on protected link:
> - When Failure of encryption occurs, kernel will change "content
> protection status" as "Enabled" -> "Disabled"
> - Kernel will try for retry for authentication and encryption.
> - If the link is encrypted once again, kernel will change
> "content protection status" as "Disabled" -> "Enabled"
> - But if retry failed, kernel will change "content
> protection" as "Desired" -> "Undesired"
> - So the "Desired" state of "content protection" property indicates
> that kernel is authenticating/re authenticating the link for encryption.
>
> --Ram
> >
> >
> >
> > > + { DRM_MODE_CONTENT_PROTECTION_DISABLE, "Disabled" },
> > > + { DRM_MODE_CONTENT_PROTECTION_ENABLE, "Enabled" },
> > > +};
> > > +DRM_ENUM_NAME_FN(drm_get_cp_status_name, drm_cp_enum_list)
> > > +
> > > /**
> > > * drm_display_info_set_bus_formats - set the supported bus formats
> > > * @info: display info to store bus formats in
> > > @@ -789,6 +796,13 @@ int drm_connector_create_standard_properties(struct drm_device *dev)
> > > return -ENOMEM;
> > > dev->mode_config.link_status_property = prop;
> > >
> > > + prop = drm_property_create_enum(dev, 0, "Content Protection",
> > > + drm_cp_enum_list,
> > > + ARRAY_SIZE(drm_cp_enum_list));
> > > + if (!prop)
> > > + return -ENOMEM;
> > > + dev->mode_config.cp_property = prop;
> > > +
> > > return 0;
> > > }
> > >
> > > diff --git a/include/drm/drm_mode_config.h b/include/drm/drm_mode_config.h
> > > index 4298171..7acb8b2 100644
> > > --- a/include/drm/drm_mode_config.h
> > > +++ b/include/drm/drm_mode_config.h
> > > @@ -538,6 +538,11 @@ struct drm_mode_config {
> > > */
> > > struct drm_property *link_status_property;
> > > /**
> > > + * @cp_property: Default connector property for CP
> > > + * of a connector
> > Can you please elaborate on this, so readers can understand how this
> > property works? Perhaps just copy the docs from the original patch?
> >
> > > + */
> > > + struct drm_property *cp_property;
> > > + /**
> > > * @plane_type_property: Default plane property to differentiate
> > > * CURSOR, PRIMARY and OVERLAY legacy uses of planes.
> > > */
> > > diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> > > index 403339f..554a770 100644
> > > --- a/include/uapi/drm/drm_mode.h
> > > +++ b/include/uapi/drm/drm_mode.h
> > > @@ -127,6 +127,11 @@ extern "C" {
> > > #define DRM_MODE_LINK_STATUS_GOOD 0
> > > #define DRM_MODE_LINK_STATUS_BAD 1
> > >
> > > +/* Content Protection options */
> > > +#define DRM_MODE_CONTENT_PROTECTION_UNSUPPORTED 0
> > > +#define DRM_MODE_CONTENT_PROTECTION_DISABLE 1
> > > +#define DRM_MODE_CONTENT_PROTECTION_ENABLE 2
> > > +
> > > /*
> > > * DRM_MODE_ROTATE_<degrees>
> > > *
> > > --
> > > 2.7.4
> > >
>
--
Sean Paul, Software Engineer, Google / Chromium OS
More information about the Intel-gfx
mailing list