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.
>> - 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,
--
Jani Nikula, Intel
