fc67615f4e
The CTA Data Block Collection is valid only for CTA extension version
3. In versions 1 and 2, it is a reserved block, which we ignore.
The DTD start offset (byte 2, or d in CTA-861 spec), which determines
the CTA Data Block Collection size, is specified slightly differently
for different versions:
Version 1:
d = offset for the byte following the reserved data block. If no
data is provided in the reserved data block, then d=4. If no DTDs
are provided, then d=0
Version 2:
d = offset for the byte following the reserved data block. If no
data is provided in the reserved data block, then d=4. If d=0, then
no detailed timing descriptors are provided, and no data is provided
in the reserved data block.
Version 3:
d = offset for the byte following the data block collection. If no
data is provided in the data block collection, then d=4. If d=0,
then no detailed timing descriptors are provided, and no data is
provided in the data block collection.
Ever since commit 9e50b9d55e ("drm: edid: Add some bounds checking"),
we've interpreted 0 to mean there are no DTDs but it's all Data
Blocks. Per the spec, Data Blocks are only valid for version 3, where we
should interpret 0 to mean there are no data blocks.
Follow the spec (and hope the EDIDs follow it too).
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/2a4c94417f024cbafc5d4ca0a74e4617fc4325d1.1654674560.git.jani.nikula@intel.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.