Fix wrong assumptions in cea_for_each_detailed_block v2
authorChristian Schmidt <schmidt@digadd.de>
Mon, 19 Dec 2011 19:03:43 +0000 (20:03 +0100)
committerDave Airlie <airlied@redhat.com>
Tue, 20 Dec 2011 09:51:10 +0000 (09:51 +0000)
commit4966b2a9351500cf36f424dfe7a683036fce5622
treec84d044d1838bb0e2184189832b4143de888923f
parenta0ab734d62ef4c35ffa5e39f9ec1e6d6284f05fa
Fix wrong assumptions in cea_for_each_detailed_block v2

The current logic misunderstands the spec about CEA 18byte descriptors.
First, the spec doesn't state "detailed timing descriptors" but "18 byte
descriptors", so any data record could be stored, mixed timings and
other data, just as in the standard EDID.
Second, the lower four bit of byte 3 of the CEA record do not contain
the number of descriptors, but "the total number of DTDs defining native
formats in the whole EDID [...], starting with the first DTD in the DTD
list (which starts in the base EDID block)." A device can of course
support non-native formats.

As such the number can't be used to determine n, and the existing code
will filter non-timing 18byte descriptors anyway.

Signed-off-by: Christian Schmidt <schmidt@digadd.de>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
drivers/gpu/drm/drm_edid.c