On 2025-11-26 16:06, Yaroslav wrote:
On 2025-11-26 15:59, Jani Nikula wrote:
On Wed, 26 Nov 2025, Yaroslav <[email protected]> wrote:
On 2025-11-26 15:08, Jani Nikula wrote:
On Wed, 26 Nov 2025, Jani Nikula <[email protected]> wrote:
On Wed, 26 Nov 2025, Yaroslav Bolyukin <[email protected]> wrote:
Current VESA vendor-specific block parsing expects real block size
to be
the same as the defined struct size, use real offsets in conditionals
instead to add struct fields in future commits.
Signed-off-by: Yaroslav Bolyukin <[email protected]>
I think this is something we want to backport, since MSO would break
with bigger vendor-specific blocks, and that leads to black screens on
MSO displays.
Cc: [email protected]
Reviewed-by: Jani Nikula <[email protected]>
Oops, I'll take that back.
---
drivers/gpu/drm/drm_edid.c | 28 ++++++++++++----------------
1 file changed, 12 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 64f7a94dd9e4..a52fd6de9327 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -6544,7 +6544,7 @@ static void
drm_parse_vesa_specific_block(struct drm_connector *connector,
if (oui(vesa->oui[0], vesa->oui[1], vesa->oui[2]) !=
VESA_IEEE_OUI)
return;
- if (sizeof(*vesa) != sizeof(*block) + block->num_bytes) {
+ if (block->num_bytes < 5) {
drm_dbg_kms(connector->dev,
"[CONNECTOR:%d:%s] Unexpected VESA vendor block
size\n",
connector->base.id, connector->name);
@@ -6567,24 +6567,20 @@ static void
drm_parse_vesa_specific_block(struct drm_connector *connector,
break;
}
- if (!info->mso_stream_count) {
- info->mso_pixel_overlap = 0;
This is no longer cleared for !info->mso_stream_count.
Perhaps the code could be reorganized to handle it better.
It defaults to zero due to drm_reset_display_info()
Yes, and the code above the context initializes it from the vendor
block.
It is wrapped in `if (info->mso_stream_count)` so we get
/* From drm_reset_display_info */
info->mso_pixel_overlap = 0;
/* This part was removed, as we don't want the early return here anymore
due to extended structure length checks
if (!info->mso_stream_count) {
info->mso_pixel_overlap = 0;
return;
} */
/* This code is right below your comment */
if (info->mso_stream_count) {
info->mso_pixel_overlap = ...;
...
}
/* I can reinsert the value reset explicitly here, if that's what you
suggesting to do:
else {
info->mso_pixel_overlap = 0;
}*/
For reference, repository state at the point after this patch:
https://github.com/CertainLach/linux-1/blob/01b0097171ebe85ae124a7b535dce0b46a1dd8e2/drivers/gpu/drm/drm_edid.c#L6561-L6593
Commit:
https://github.com/CertainLach/linux-1/commit/01b0097171ebe85ae124a7b535dce0b46a1dd8e2
(Note that the fix for DP/EDP mistake is already here, but nothing else
was changed in the github version of this patch)
- return;
- }
-
- info->mso_pixel_overlap =
FIELD_GET(DISPLAYID_VESA_MSO_OVERLAP, vesa->mso);
- if (info->mso_pixel_overlap > 8) {
+ if (info->mso_stream_count) {
+ info->mso_pixel_overlap =
FIELD_GET(DISPLAYID_VESA_MSO_OVERLAP, vesa->mso);
+ if (info->mso_pixel_overlap > 8) {
+ drm_dbg_kms(connector->dev,
+ "[CONNECTOR:%d:%s] Reserved MSO pixel overlap
value %u\n",
+ connector->base.id, connector->name,
+ info->mso_pixel_overlap);
+ info->mso_pixel_overlap = 8;
+ }
drm_dbg_kms(connector->dev,
- "[CONNECTOR:%d:%s] Reserved MSO pixel overlap
value %u\n",
+ "[CONNECTOR:%d:%s] MSO stream count %u, pixel
overlap %u\n",
connector->base.id, connector->name,
- info->mso_pixel_overlap);
- info->mso_pixel_overlap = 8;
+ info->mso_stream_count, info->mso_pixel_overlap);
}
-
- drm_dbg_kms(connector->dev,
- "[CONNECTOR:%d:%s] MSO stream count %u, pixel overlap
%u\n",
- connector->base.id, connector->name,
- info->mso_stream_count, info->mso_pixel_overlap);
}
static void drm_update_vesa_specific_block(struct drm_connector
*connector,
