On Tue, 02 Dec 2025, Yaroslav Bolyukin <[email protected]> wrote:
> As per DisplayID v2.1a spec:
> If Offset 06h[2:0] is programmed to 001b (External DisplayPort), this
> field shall be cleared to 00b (Not supported).
>
> Link: 
> https://lore.kernel.org/lkml/[email protected]/

The Link: tag is unnecessary. No need to resend for this.

Reviewed-by: Jani Nikula <[email protected]>


> Signed-off-by: Yaroslav Bolyukin <[email protected]>
> ---
>  drivers/gpu/drm/drm_displayid_internal.h |  4 +++
>  drivers/gpu/drm/drm_edid.c               | 36 +++++++++++++++---------
>  2 files changed, 27 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_displayid_internal.h 
> b/drivers/gpu/drm/drm_displayid_internal.h
> index 5b1b32f73516..72f107ae832f 100644
> --- a/drivers/gpu/drm/drm_displayid_internal.h
> +++ b/drivers/gpu/drm/drm_displayid_internal.h
> @@ -142,9 +142,13 @@ struct displayid_formula_timing_block {
>       struct displayid_formula_timings_9 timings[];
>  } __packed;
>  
> +#define DISPLAYID_VESA_DP_TYPE               GENMASK(2, 0)
>  #define DISPLAYID_VESA_MSO_OVERLAP   GENMASK(3, 0)
>  #define DISPLAYID_VESA_MSO_MODE              GENMASK(6, 5)
>  
> +#define DISPLAYID_VESA_DP_TYPE_EDP   0
> +#define DISPLAYID_VESA_DP_TYPE_DP    1
> +
>  struct displayid_vesa_vendor_specific_block {
>       struct displayid_block base;
>       u8 oui[3];
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index a0a6ccf12475..380a9dda275f 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -6533,6 +6533,7 @@ static void drm_parse_vesa_specific_block(struct 
> drm_connector *connector,
>       struct displayid_vesa_vendor_specific_block *vesa =
>               (struct displayid_vesa_vendor_specific_block *)block;
>       struct drm_display_info *info = &connector->display_info;
> +     int dp_type;
>  
>       if (block->num_bytes < 3) {
>               drm_dbg_kms(connector->dev,
> @@ -6551,20 +6552,29 @@ static void drm_parse_vesa_specific_block(struct 
> drm_connector *connector,
>               return;
>       }
>  
> -     switch (FIELD_GET(DISPLAYID_VESA_MSO_MODE, vesa->mso)) {
> -     default:
> -             drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] Reserved MSO 
> mode value\n",
> +     dp_type = FIELD_GET(DISPLAYID_VESA_DP_TYPE, vesa->data_structure_type);
> +     if (dp_type > 1) {
> +             drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] Reserved dp type 
> value\n",
>                           connector->base.id, connector->name);
> -             fallthrough;
> -     case 0:
> -             info->mso_stream_count = 0;
> -             break;
> -     case 1:
> -             info->mso_stream_count = 2; /* 2 or 4 links */
> -             break;
> -     case 2:
> -             info->mso_stream_count = 4; /* 4 links */
> -             break;
> +     }
> +
> +     /* MSO is only supported for eDP */
> +     if (dp_type == DISPLAYID_VESA_DP_TYPE_EDP) {
> +             switch (FIELD_GET(DISPLAYID_VESA_MSO_MODE, vesa->mso)) {
> +             default:
> +                     drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] Reserved 
> MSO mode value\n",
> +                                 connector->base.id, connector->name);
> +                     fallthrough;
> +             case 0:
> +                     info->mso_stream_count = 0;
> +                     break;
> +             case 1:
> +                     info->mso_stream_count = 2; /* 2 or 4 links */
> +                     break;
> +             case 2:
> +                     info->mso_stream_count = 4; /* 4 links */
> +                     break;
> +             }
>       }
>  
>       if (info->mso_stream_count) {

-- 
Jani Nikula, Intel

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