This is a note to let you know that I've just added the patch titled
drm/edid: Parse topology block for all DispID structure v1.x
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-edid-parse-topology-block-for-all-dispid-structu.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 4a806e68343a5f5ac4522e6f190e96473d6bbc2f
Author: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Date: Wed Apr 10 21:01:39 2024 +0300
drm/edid: Parse topology block for all DispID structure v1.x
[ Upstream commit e0a200ab4b72afd581bd6f82fc1ef510a4fb5478 ]
DisplayID spec v1.3 revision history notes do claim that
the toplogy block was added in v1.3 so requiring structure
v1.2 would seem correct, but there is at least one EDID in
edid.tv with a topology block and structure v1.0. And
there are also EDIDs with DisplayID structure v1.3 which
seems to be totally incorrect as DisplayID spec v1.3 lists
structure v1.2 as the only legal value.
Unfortunately I couldn't find copies of DisplayID spec
v1.0-v1.2 anywhere (even on vesa.org), so I'll have to
go on empirical evidence alone.
We used to parse the topology block on all v1.x
structures until the check for structure v2.0 was added.
Let's go back to doing that as the evidence does suggest
that there are DisplayIDs in the wild that would miss
out on the topology stuff otherwise.
Also toss out DISPLAY_ID_STRUCTURE_VER_12 entirely as
it doesn't appear we can really use it for anything.
I *think* we could technically skip all the structure
version checks as the block tags shouldn't conflict
between v2.0 and v1.x. But no harm in having a bit of
extra sanity checks I guess.
So far I'm not aware of any user reported regressions
from overly strict check, but I do know that it broke
igt/kms_tiled_display's fake DisplayID as that one
gets generated with structure v1.0.
Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
Cc: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
Fixes: c5a486af9df7 ("drm/edid: parse Tiled Display Topology Data Block for DisplayID 2.0")
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20240410180139.21352-1-ville.syrjala@xxxxxxxxxxxxxxx
Acked-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index a491280ca48c8..ee3fab115c4b5 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -7321,7 +7321,7 @@ static void drm_parse_tiled_block(struct drm_connector *connector,
static bool displayid_is_tiled_block(const struct displayid_iter *iter,
const struct displayid_block *block)
{
- return (displayid_version(iter) == DISPLAY_ID_STRUCTURE_VER_12 &&
+ return (displayid_version(iter) < DISPLAY_ID_STRUCTURE_VER_20 &&
block->tag == DATA_BLOCK_TILED_DISPLAY) ||
(displayid_version(iter) == DISPLAY_ID_STRUCTURE_VER_20 &&
block->tag == DATA_BLOCK_2_TILED_DISPLAY_TOPOLOGY);
diff --git a/include/drm/drm_displayid.h b/include/drm/drm_displayid.h
index 566497eeb3b81..bc1f6b378195f 100644
--- a/include/drm/drm_displayid.h
+++ b/include/drm/drm_displayid.h
@@ -30,7 +30,6 @@ struct drm_edid;
#define VESA_IEEE_OUI 0x3a0292
/* DisplayID Structure versions */
-#define DISPLAY_ID_STRUCTURE_VER_12 0x12
#define DISPLAY_ID_STRUCTURE_VER_20 0x20
/* DisplayID Structure v1r2 Data Blocks */
