On Wed, 26 Nov 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]/
> 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 a52fd6de9327..348aa31aea1b 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 not supported for eDP */
> + if (dp_type != DISPLAYID_VESA_DP_TYPE_EDP) {
MSO is *only* supported on eDP, not the other way round!
BR,
Jani.
> + 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
