Re: [PATCH v3 06/10] drm: Add CP downstream_info property

Ramalingam C
2019-03-27T14:00:13Z

On 2019-03-27 at 11:25:04 +0100, Daniel Vetter wrote:
> On Fri, Mar 22, 2019 at 06:14:44AM +0530, Ramalingam C wrote:
> > This patch adds a optional CP downstream info blob property to the
> > connectors. This enables the Userspace to read the information of HDCP
> > authenticated downstream topology.
> >
> > Driver will updated this blob with all downstream information at the
> > end of the authentication.
> >
> > In case userspace configures this platform as repeater, then this
> > information is needed for the authentication with upstream HDCP
> > transmitter.
> >
> > v2:
> > s/cp_downstream/content_protection_downstream [daniel]
> > v3:
> > s/content_protection_downstream/hdcp_topology [daniel]
> >
> > Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
> > ---
> > drivers/gpu/drm/drm_atomic_uapi.c | 4 ++
> > drivers/gpu/drm/drm_connector.c | 86 +++++++++++++++++++++++++++++++
> > include/drm/drm_connector.h | 12 +++++
> > include/uapi/drm/drm_mode.h | 27 ++++++++++
> > 4 files changed, 129 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> > index 857ca6fa6fd0..4246e8988c29 100644
> > --- a/drivers/gpu/drm/drm_atomic_uapi.c
> > +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> > @@ -826,6 +826,10 @@ drm_atomic_connector_get_property(struct drm_connector *connector,
> > *val = state->content_protection;
> > } else if (property == connector->hdcp_content_type_property) {
> > *val = state->hdcp_content_type;
> > + } else if (property ==
> > + connector->hdcp_topology_property) {
> > + *val = connector->hdcp_topology_blob_ptr ?
> > + connector->hdcp_topology_blob_ptr->base.id : 0;
> > } 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 ff61c3208307..0de8b441a449 100644
> > --- a/drivers/gpu/drm/drm_connector.c
> > +++ b/drivers/gpu/drm/drm_connector.c
> > @@ -246,6 +246,7 @@ int drm_connector_init(struct drm_device *dev,
> > mutex_init(&connector->mutex);
> > connector->edid_blob_ptr = NULL;
> > connector->tile_blob_ptr = NULL;
> > + connector->hdcp_topology_blob_ptr = NULL;
> > connector->status = connector_status_unknown;
> > connector->display_info.panel_orientation =
> > DRM_MODE_PANEL_ORIENTATION_UNKNOWN;
> > @@ -986,6 +987,25 @@ DRM_ENUM_NAME_FN(drm_get_hdcp_content_type_name,
> > * authentication process. 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
> > + * HDCP Topology:
> > + * This blob property is used to pass the HDCP downstream topology details
> > + * of a HDCP encrypted connector, from kernel to userspace.
> > + * This provides all required information to userspace, so that userspace
> > + * can implement the HDCP repeater using the kernel as downstream ports of
> > + * the repeater. as illustrated below:
> > + *
> > + * HDCP Repeaters
> > + * +--------------------------------------------------------------+
> > + * | |
> > + * | | |
> > + * | Userspace HDCP Receiver +-----> KMD HDCP transmitters |
> > + * | (Upstream Port) <------+ (Downstream Ports) |
> > + * | | |
> > + * | |
> > + * +--------------------------------------------------------------+
>
> I didn't check, but I think this doesn't format correctly in the html
> output. I think you need to indent, and start with :: to denote a fixed
> width font example.
Looks good at mutt and at
https://patchwork.freedesktop.org/patch/293490/?series=57232&rev=4
Should i still do something on it?
>
> > + *
> > + * Kernel will populate this blob only when the HDCP authentication is
> > + * successful.
> > *
> > * max bpc:
> > * This range property is used by userspace to limit the bit depth. When
> > @@ -1614,6 +1634,72 @@ drm_connector_attach_hdcp_content_type_property(struct drm_connector *
> > }
> > EXPORT_SYMBOL(drm_connector_attach_hdcp_content_type_property);
> >
> > +/**
> > + * drm_connector_attach_hdcp_topology_property - attach hdcp topology property
> > + *
> > + * @connector: connector to attach hdcp topology property with.
> > + *
> > + * This is used to add support for hdcp topology support on select connectors.
> > + * When Intel platform is configured as repeater, this downstream info is used
> > + * by userspace, to complete the repeater authentication of HDCP specification
> > + * with upstream HDCP transmitter.
> > + *
> > + * The blob_id of the hdcp topology info will be set to
> > + * &drm_connector_state.hdcp_topology
> > + *
> > + * Returns:
> > + * Zero on success, negative errno on failure.
> > + */
> > +int drm_connector_attach_hdcp_topology_property(struct drm_connector *connector)
> > +{
> > + struct drm_device *dev = connector->dev;
> > + struct drm_property *prop;
> > +
> > + prop = drm_property_create(dev, DRM_MODE_PROP_BLOB |
> > + DRM_MODE_PROP_IMMUTABLE,
> > + "HDCP Topology", 0);
>
> Again global prop in dev->mode_config, and I think just add a flag to the
> overall "attach content protection stuff to connnector" function.
Will be done in the next version :)

-Ram
>
> > + if (!prop)
> > + return -ENOMEM;
> > +
> > + drm_object_attach_property(&connector->base, prop, 0);
> > +
> > + connector->hdcp_topology_property = prop;
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL(drm_connector_attach_hdcp_topology_property);
> > +
> > +/**
> > + * drm_connector_update_hdcp_topology_property - update the hdcp topology
> > + * property of a connector
> > + * @connector: drm connector, the topology is associated to
> > + * @hdcp_topology_info: new content for the blob of hdcp_topology property
> > + *
> > + * This function creates a new blob modeset object and assigns its id to the
> > + * connector's hdcp_topology property.
> > + *
> > + * Returns:
> > + * Zero on success, negative errno on failure.
> > + */
> > +int
> > +drm_connector_update_hdcp_topology_property(struct drm_connector *connector,
> > + const struct hdcp_topology_info *info)
> > +{
> > + struct drm_device *dev = connector->dev;
> > + int ret;
> > +
> > + if (!info)
> > + return -EINVAL;
> > +
> > + ret = drm_property_replace_global_blob(dev,
> > + &connector->hdcp_topology_blob_ptr,
> > + sizeof(struct hdcp_topology_info),
> > + info, &connector->base,
> > + connector->hdcp_topology_property);
> > + return ret;
> > +}
> > +EXPORT_SYMBOL(drm_connector_update_hdcp_topology_property);
> > +
> > /**
> > * drm_mode_create_aspect_ratio_property - create aspect ratio property
> > * @dev: DRM device
> > diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> > index f0830985367f..c016a0bcedac 100644
> > --- a/include/drm/drm_connector.h
> > +++ b/include/drm/drm_connector.h
> > @@ -1047,6 +1047,13 @@ struct drm_connector {
> > */
> > struct drm_property *hdcp_content_type_property;
> >
> > + /**
> > + * @hdcp_topology_property: DRM BLOB property for hdcp downstream
> > + * topology information.
> > + */
> > + struct drm_property *hdcp_topology_property;
> > + struct drm_property_blob *hdcp_topology_blob_ptr;
>
> Need kerneldoc for both or kerneldoc gets a bit unhappy.
Sure.
>
> > +
> > /**
> > * @path_blob_ptr:
> > *
> > @@ -1324,6 +1331,11 @@ int drm_connector_attach_content_protection_property(
> > struct drm_connector *connector);
> > int drm_connector_attach_hdcp_content_type_property(
> > struct drm_connector *connector);
> > +int drm_connector_attach_hdcp_topology_property(
> > + struct drm_connector *connector);
> > +int drm_connector_update_hdcp_topology_property(
> > + struct drm_connector *connector,
> > + const struct hdcp_topology_info *info);
> > int drm_mode_create_aspect_ratio_property(struct drm_device *dev);
> > int drm_mode_create_colorspace_property(struct drm_connector *connector);
> > int drm_mode_create_content_type_property(struct drm_device *dev);
> > diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> > index 44412e8b77cd..03d3aa2b1a49 100644
> > --- a/include/uapi/drm/drm_mode.h
> > +++ b/include/uapi/drm/drm_mode.h
> > @@ -214,6 +214,33 @@ extern "C" {
> > #define DRM_MODE_HDCP_CONTENT_TYPE0 0
> > #define DRM_MODE_HDCP_CONTENT_TYPE1 1
> >
> > +#define DRM_MODE_HDCP_KSV_LEN 5
> > +#define DRM_MODE_HDCP_MAX_DEVICE_CNT 127
> > +
> > +struct hdcp_topology_info {
> > + /* KSV of immediate HDCP Sink. In Little-Endian Format. */
> > + char bksv[DRM_MODE_HDCP_KSV_LEN];
>
> This isn't aligned to __u32. Just make the length 128 bytes.
>
> > +
> > + /* Whether Immediate HDCP sink is a repeater? */
> > + bool is_repeater;
>
> no bool in uapi structs. Just go with __u8.
>
> > +
> > + /* Depth received from immediate downstream repeater */
> > + __u8 depth;
>
> Needs to be aligned with explicit padding.
not sure why do we need this explicit padding. currently this struct
works between IGT and kernel. Might be co-incident too!!

Will check on this.
>
> > +
> > + /* Device count received from immediate downstream repeater */
> > + __u32 device_count;
> > +
> > + /*
> > + * Max buffer required to hold ksv list received from immediate
> > + * repeater. In this array first device_count * DRM_MODE_HDCP_KSV_LEN
> > + * will hold the valid ksv bytes.
> > + * If authentication specification is
> > + * HDCP1.4 - each KSV's Bytes will be in Little-Endian format.
> > + * HDCP2.2 - each KSV's Bytes will be in Big-Endian format.
>
> Why is this ksv list be for hdcp2.2, but bksv is le for both case? I'm
> confused.
I used the KSV and receiver ID interchangeably. receiver ID/KSV lists
from repeater changes with endianness. I guess we need not bother about
it at present.
>
> > + */
> > + char ksv_list[DRM_MODE_HDCP_KSV_LEN * DRM_MODE_HDCP_MAX_DEVICE_CNT];
>
> Again better to align this. Also maybe make it a nested array (it's the
> same underlying layout, but easier to use for userspace.)
>
> For uapi struct recommendations, see https://gitlab.com/TeeFirefly/linux-kernel/blob/7408b38cfdf9b0c6c3bda97402c75bd27ef69a85/Documentation/ioctl/botching-up-ioctls.txt
I will go through and align to it. Thanks for sharing.

-Ram
>
> Cheers, Daniel
> > +};
> > +
> > struct drm_mode_modeinfo {
> > __u32 clock;
> > __u16 hdisplay;
> > --
> > 2.19.1
> >
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch