Commit a6315ec2 authored Oct 24, 2023 by Imre Deak

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

parent b3481504

drivers/gpu/drm/display/drm_dp_helper.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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) },
		};

include/drm/display/drm_dp_helper.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -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,
		};

		/**