drm/dp_mst: Add HBLANK expansion quirk for Synaptics MST hubs

Add a quirk for Synaptics MST hubs, which require a workaround - at leat
on i915 - for some modes, on which the hub applies HBLANK expansion.
These modes will only work by enabling DSC decompression for them, a
follow-up patch will do this in i915.

v2:
- Fix the quirk name in its DocBook description.

Cc: Lyude Paul <lyude@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231030155843.2251023-9-imre.deak@intel.com

diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index 8a1b64c57dfdb42d52c2a6983d80533370a10d8a..2a95a05f0437ec3e65e815704afd9de4fc240f64 100644 (file)
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -2242,6 +2242,8 @@ static const struct dpcd_quirk dpcd_quirk_list[] = {
        { OUI(0x00, 0x00, 0x00), DEVICE_ID('C', 'H', '7', '5', '1', '1'), false, BIT(DP_DPCD_QUIRK_NO_SINK_COUNT) },
        /* Synaptics DP1.4 MST hubs can support DSC without virtual DPCD */
        { OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) },
+       /* Synaptics DP1.4 MST hubs require DSC for some modes on which it applies HBLANK expansion. */
+       { OUI(0x90, 0xCC, 0x24), DEVICE_ID_ANY, true, BIT(DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC) },
        /* Apple MacBookPro 2017 15 inch eDP Retina panel reports too low DP_MAX_LINK_RATE */
        { OUI(0x00, 0x10, 0xfa), DEVICE_ID(101, 68, 21, 101, 98, 97), false, BIT(DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS) },
 };

diff --git a/include/drm/display/drm_dp_helper.h b/include/drm/display/drm_dp_helper.h
index 3369104e2d257c072e784e6b12f71f6cb12cd1ff..01636a679ee6c4b1669ecbf1e2c4bab4fcc6b3c6 100644 (file)
--- a/include/drm/display/drm_dp_helper.h
+++ b/include/drm/display/drm_dp_helper.h
@@ -632,6 +632,13 @@ enum drm_dp_quirk {
         * the DP_MAX_LINK_RATE register reporting a lower max multiplier.
         */
        DP_DPCD_QUIRK_CAN_DO_MAX_LINK_RATE_3_24_GBPS,
+       /**
+        * @DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC:
+        *
+        * The device applies HBLANK expansion for some modes, but this
+        * requires enabling DSC.
+        */
+       DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC,
 };
 
 /**