From 5e9ef795ed5780e772b31d141a4557707c6c9fee Mon Sep 17 00:00:00 2001
From: Sankeerth Billakanti <quic_sbillaka@quicinc.com>
Date: Tue, 2 Nov 2021 13:18:45 +0530
Subject: drm/msm/dp: Enable ASSR for supported DP sinks
Git-commit: 016aa55082c2dd16e438e18e23f8bd8a67f30d84
Patch-mainline: v5.17-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

The eDP sink on sc7280 supports ASSR and dp driver will
enable ASSR in the source hardware. The driver needs to
enable the ASSR field in the DPCD configuration register
to avoid screen corruption. This change will enable ASSR
if supported in the sink device.

Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/1635839325-401-6-git-send-email-quic_sbillaka@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/msm/dp/dp_ctrl.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index a40e79871012..c724cb0bde9d 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -119,13 +119,13 @@ void dp_ctrl_push_idle(struct dp_ctrl *dp_ctrl)
 static void dp_ctrl_config_ctrl(struct dp_ctrl_private *ctrl)
 {
 	u32 config = 0, tbd;
-	u8 *dpcd = ctrl->panel->dpcd;
+	const u8 *dpcd = ctrl->panel->dpcd;
 
 	/* Default-> LSCLK DIV: 1/4 LCLK  */
 	config |= (2 << DP_CONFIGURATION_CTRL_LSCLK_DIV_SHIFT);
 
 	/* Scrambler reset enable */
-	if (dpcd[DP_EDP_CONFIGURATION_CAP] & DP_ALTERNATE_SCRAMBLER_RESET_CAP)
+	if (drm_dp_alternate_scrambler_reset_cap(dpcd))
 		config |= DP_CONFIGURATION_CTRL_ASSR;
 
 	tbd = dp_link_get_test_bits_depth(ctrl->link,
@@ -1231,6 +1231,7 @@ static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl,
 	const u8 *dpcd = ctrl->panel->dpcd;
 	u8 encoding = DP_SET_ANSI_8B10B;
 	u8 ssc;
+	u8 assr;
 	struct dp_link_info link_info = {0};
 
 	dp_ctrl_config_ctrl(ctrl);
@@ -1249,6 +1250,12 @@ static int dp_ctrl_link_train(struct dp_ctrl_private *ctrl,
 	drm_dp_dpcd_write(ctrl->aux, DP_MAIN_LINK_CHANNEL_CODING_SET,
 				&encoding, 1);
 
+	if (drm_dp_alternate_scrambler_reset_cap(dpcd)) {
+		assr = DP_ALTERNATE_SCRAMBLER_RESET_ENABLE;
+		drm_dp_dpcd_write(ctrl->aux, DP_EDP_CONFIGURATION_SET,
+				&assr, 1);
+	}
+
 	ret = dp_ctrl_link_train_1(ctrl, training_step);
 	if (ret) {
 		DRM_ERROR("link training #1 failed. ret=%d\n", ret);
-- 
2.38.1