From: Ville Syrjälä ville.syrjala@linux.intel.com
stable inclusion from stable-v6.6.33 commit 6040fcea46055159c5cafc95cd6f63e06028086b category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAD6H2
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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[ 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@intel.com Cc: Dmitry Osipenko dmitry.osipenko@collabora.com Fixes: c5a486af9df7 ("drm/edid: parse Tiled Display Topology Data Block for DisplayID 2.0") Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20240410180139.21352-1-ville.s... Acked-by: Jani Nikula jani.nikula@intel.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Wang Hai wanghai38@huawei.com --- drivers/gpu/drm/drm_edid.c | 2 +- include/drm/drm_displayid.h | 1 - 2 files changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index a491280ca48c..ee3fab115c4b 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 566497eeb3b8..bc1f6b378195 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 */