From: jsg <jsg@openbsd.org>
Date: Wed, 9 Feb 2022 04:25:22 +0000 (+0000)
Subject: drm/amd/display: Force link_rate as LINK_RATE_RBR2 for 2018 15" Apple Retina panels
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=03dc15f4a55cd3ab8f18e3344414bfea38fc3a12;p=openbsd

drm/amd/display: Force link_rate as LINK_RATE_RBR2 for 2018 15" Apple Retina panels

From Aun-Ali Zaidi
2093ecf557e733f995c7db6df716c91c43923972 in linux 5.15.y/5.15.22
30fbce374745a9c6af93c775a5ac49a97f822fda in mainline linux
---

diff --git a/sys/dev/pci/drm/amd/display/dc/core/dc_link_dp.c b/sys/dev/pci/drm/amd/display/dc/core/dc_link_dp.c
index d6405b07785..095020648a3 100644
--- a/sys/dev/pci/drm/amd/display/dc/core/dc_link_dp.c
+++ b/sys/dev/pci/drm/amd/display/dc/core/dc_link_dp.c
@@ -3913,6 +3913,26 @@ static bool retrieve_link_cap(struct dc_link *link)
 		dp_hw_fw_revision.ieee_fw_rev,
 		sizeof(dp_hw_fw_revision.ieee_fw_rev));
 
+	/* Quirk for Apple MBP 2018 15" Retina panels: wrong DP_MAX_LINK_RATE */
+	{
+		uint8_t str_mbp_2018[] = { 101, 68, 21, 103, 98, 97 };
+		uint8_t fwrev_mbp_2018[] = { 7, 4 };
+		uint8_t fwrev_mbp_2018_vega[] = { 8, 4 };
+
+		/* We also check for the firmware revision as 16,1 models have an
+		 * identical device id and are incorrectly quirked otherwise.
+		 */
+		if ((link->dpcd_caps.sink_dev_id == 0x0010fa) &&
+		    !memcmp(link->dpcd_caps.sink_dev_id_str, str_mbp_2018,
+			     sizeof(str_mbp_2018)) &&
+		    (!memcmp(link->dpcd_caps.sink_fw_revision, fwrev_mbp_2018,
+			     sizeof(fwrev_mbp_2018)) ||
+		    !memcmp(link->dpcd_caps.sink_fw_revision, fwrev_mbp_2018_vega,
+			     sizeof(fwrev_mbp_2018_vega)))) {
+			link->reported_link_cap.link_rate = LINK_RATE_RBR2;
+		}
+	}
+
 	memset(&link->dpcd_caps.dsc_caps, '\0',
 			sizeof(link->dpcd_caps.dsc_caps));
 	memset(&link->dpcd_caps.fec_cap, '\0', sizeof(link->dpcd_caps.fec_cap));