DRM database property: HDCP Content Type

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Details

Name

HDCP Content Type

Flags

<none>

Type

enum

Attached to

connector

Specification

{"HDCP Type0", "HDCP Type1"}

Documentation

This Enum property is used by the userspace to declare the content type
of the display stream, to kernel. Here display stream stands for any
display content that userspace intended to display through HDCP
encryption.

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 of the below:
  - "HDCP Type0": DRM_MODE_HDCP_CONTENT_TYPE0 = 0
  - "HDCP Type1": DRM_MODE_HDCP_CONTENT_TYPE1 = 1

When kernel starts the HDCP authentication (see "Content Protection"
for details), it uses the content type in "HDCP Content Type"
for performing the HDCP authentication with the display sink.

Please note in HDCP spec versions, a link can be authenticated with
HDCP 2.2 for Content Type 0/Content Type 1. Where as a link can be
authenticated with HDCP1.4 only for Content Type 0(though it is implicit
in nature. As there is no reference for Content Type in HDCP1.4).

HDCP2.2 authentication protocol itself takes the "Content Type" as a
parameter, which is a input for the DP HDCP2.2 encryption algo.

In case of Type 0 content protection request, kernel driver can choose
either of HDCP spec versions 1.4 and 2.2. When HDCP2.2 is used for
"HDCP Type 0", a HDCP 2.2 capable repeater in the downstream can send
that content to a HDCP 1.4 authenticated HDCP sink (Type0 link).
But if the content is classified as "HDCP Type 1", above mentioned
HDCP 2.2 repeater wont send the content to the HDCP sink as it can't
authenticate the HDCP1.4 capable sink for "HDCP Type 1".

Please note userspace can be ignorant of the HDCP versions used by the
kernel driver to achieve the "HDCP Content Type".

At current scenario, classifying a content as Type 1 ensures that the
content will be displayed only through the HDCP2.2 encrypted link.

Note that the HDCP Content Type property is introduced at HDCP 2.2, and
defaults to type 0. It is only exposed by drivers supporting HDCP 2.2
(hence supporting Type 0 and Type 1). Based on how next versions of
HDCP specs are defined content Type could be used for higher versions
too.

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. And when "Content Protection" is ENABLED, it means
that link is HDCP authenticated and encrypted, for the transmission of
the Type of stream mentioned at "HDCP Content Type".

Driver support