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.
Cc: Lyude Paul <lyude@xxxxxxxxxx>
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
---
drivers/gpu/drm/display/drm_dp_helper.c | 2 ++
include/drm/display/drm_dp_helper.h | 7 +++++++
2 files changed, 9 insertions(+)
diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c
index f3680f4e69708..e5d7970a9ddd0 100644
--- a/drivers/gpu/drm/display/drm_dp_helper.c
+++ b/drivers/gpu/drm/display/drm_dp_helper.c
@@ -2245,6 +2245,8 @@ 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 3d74b2cec72fd..351f38d5cc351 100644
--- 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_NEEDS_DSC:
+ *
+ * The device applies HBLANK expansion for some modes, but this
+ * requires enabling DSC.
+ */
+ DP_DPCD_QUIRK_HBLANK_EXPANSION_REQUIRES_DSC,
};
/**
--
2.39.2
