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.
>
>>>> - 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
