From: Vladimir Stempen <vladimir.stempen@amd.com>
Date: Tue, 28 Apr 2020 17:04:35 +0000 (-0400)
Subject: drm/amd/display: DP training to set properly SCRAMBLING_DISABLE
X-Git-Tag: v5.15~3752^2^2~21
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=7d1ee78f033a1b478cfa78eb4e11dd40e060f977;p=mirror_ubuntu-kernels.git

drm/amd/display: DP training to set properly SCRAMBLING_DISABLE

[Why]
DP training sequence to set SCRAMBLING_DISABLE bit properly based on
training pattern - per DP Spec.

[How]
Update dpcd_pattern.v1_4.SCRAMBLING_DISABLE with 1 for TPS1, TPS2, TPS3,
but not for TPS4.

Signed-off-by: Vladimir Stempen <vladimir.stempen@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index 1db592372435..91cd884d6f25 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -219,6 +219,30 @@ static enum dpcd_training_patterns
 	return dpcd_tr_pattern;
 }
 
+static uint8_t dc_dp_initialize_scrambling_data_symbols(
+	struct dc_link *link,
+	enum dc_dp_training_pattern pattern)
+{
+	uint8_t disable_scrabled_data_symbols = 0;
+
+	switch (pattern) {
+	case DP_TRAINING_PATTERN_SEQUENCE_1:
+	case DP_TRAINING_PATTERN_SEQUENCE_2:
+	case DP_TRAINING_PATTERN_SEQUENCE_3:
+		disable_scrabled_data_symbols = 1;
+		break;
+	case DP_TRAINING_PATTERN_SEQUENCE_4:
+		disable_scrabled_data_symbols = 0;
+		break;
+	default:
+		ASSERT(0);
+		DC_LOG_HW_LINK_TRAINING("%s: Invalid HW Training pattern: %d\n",
+			__func__, pattern);
+		break;
+	}
+	return disable_scrabled_data_symbols;
+}
+
 static inline bool is_repeater(struct dc_link *link, uint32_t offset)
 {
 	return (!link->is_lttpr_mode_transparent && offset != 0);
@@ -251,6 +275,9 @@ static void dpcd_set_lt_pattern_and_lane_settings(
 	dpcd_pattern.v1_4.TRAINING_PATTERN_SET =
 		dc_dp_training_pattern_to_dpcd_training_pattern(link, pattern);
 
+	dpcd_pattern.v1_4.SCRAMBLING_DISABLE =
+		dc_dp_initialize_scrambling_data_symbols(link, pattern);
+
 	dpcd_lt_buffer[DP_TRAINING_PATTERN_SET - DP_TRAINING_PATTERN_SET]
 		= dpcd_pattern.raw;