From: Tomi Valkeinen <tomi.valkeinen@ti.com>
Date: Tue, 28 May 2019 08:27:25 +0000 (+0300)
Subject: drm/bridge: tc358767: reset voltage-swing & pre-emphasis
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=c28d14849d374c89ae17134a5bc4a3818fe72467;p=openwrt%2Fstaging%2Fblogic.git

drm/bridge: tc358767: reset voltage-swing & pre-emphasis

We need to reset DPCD voltage-swing & pre-emphasis before starting the
link training, as otherwise tc358767 will use the previous values as
minimums.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528082747.3631-3-tomi.valkeinen@ti.com
---

diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
index b6c4d1063ccb..c8b04f711db3 100644
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -956,6 +956,13 @@ static int tc_main_link_setup(struct tc_data *tc)
 	if (ret < 0)
 		goto err_dpcd_write;
 
+	/* Reset voltage-swing & pre-emphasis */
+	tmp[0] = tmp[1] = DP_TRAIN_VOLTAGE_SWING_LEVEL_0 |
+			  DP_TRAIN_PRE_EMPH_LEVEL_0;
+	ret = drm_dp_dpcd_write(aux, DP_TRAINING_LANE0_SET, tmp, 2);
+	if (ret < 0)
+		goto err_dpcd_write;
+
 	ret = tc_link_training(tc, DP_TRAINING_PATTERN_1);
 	if (ret)
 		goto err;