linux-kernel - [PATCH AUTOSEL 6.1 04/58] drm/amd/display: Revert Reduce delay when sink device not able to ACK 00340h write

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Message-Id: <20230227020457.1048737-4-sashal@kernel.org>
Date:   Sun, 26 Feb 2023 21:04:02 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Ian Chen <ian.chen@....com>, Wayne Lin <Wayne.Lin@....com>,
        Jasdeep Dhillon <jdhillon@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>, harry.wentland@....com,
        sunpeng.li@....com, Rodrigo.Siqueira@....com,
        christian.koenig@....com, Xinhui.Pan@....com, airlied@...il.com,
        daniel@...ll.ch, wenjing.liu@....com, HaoPing.Liu@....com,
        George.Shen@....com, dingchen.zhang@....com,
        Iswara.Nagulendran@....com, Evgenii.Krasnikov@....com,
        michael.strauss@....com, Jimmy.Kizito@....com,
        qingqing.zhuo@....com, arnd@...db.de, sungkim@....com,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.1 04/58] drm/amd/display: Revert Reduce delay when sink device not able to ACK 00340h write

From: Ian Chen <ian.chen@....com>

[ Upstream commit 639f6ad6df7f47db48b59956b469a6917a136afb ]

[WHY]
It causes regression AMD source will not write DPCD 340.

Reviewed-by: Wayne Lin <Wayne.Lin@....com>
Acked-by: Jasdeep Dhillon <jdhillon@....com>
Signed-off-by: Ian Chen <ian.chen@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link.c    |  6 ------
 drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 14 +++-----------
 drivers/gpu/drm/amd/display/dc/dc_dp_types.h     |  1 -
 3 files changed, 3 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index 40b9d2ce08e66..328c5e33cc66b 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -1916,12 +1916,6 @@ struct dc_link *link_create(const struct link_init_data *init_params)
 	if (false == dc_link_construct(link, init_params))
 		goto construct_fail;
 
-	/*
-	 * Must use preferred_link_setting, not reported_link_cap or verified_link_cap,
-	 * since struct preferred_link_setting won't be reset after S3.
-	 */
-	link->preferred_link_setting.dpcd_source_device_specific_field_support = true;
-
 	return link;
 
 construct_fail:
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 1254d38f1778a..24f1aba4ae133 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
@@ -6591,18 +6591,10 @@ void dpcd_set_source_specific_data(struct dc_link *link)
 
 			uint8_t hblank_size = (uint8_t)link->dc->caps.min_horizontal_blanking_period;
 
-			if (link->preferred_link_setting.dpcd_source_device_specific_field_support) {
-				result_write_min_hblank = core_link_write_dpcd(link,
-					DP_SOURCE_MINIMUM_HBLANK_SUPPORTED, (uint8_t *)(&hblank_size),
-					sizeof(hblank_size));
-
-				if (result_write_min_hblank == DC_ERROR_UNEXPECTED)
-					link->preferred_link_setting.dpcd_source_device_specific_field_support = false;
-			} else {
-				DC_LOG_DC("Sink device does not support 00340h DPCD write. Skipping on purpose.\n");
-			}
+			result_write_min_hblank = core_link_write_dpcd(link,
+				DP_SOURCE_MINIMUM_HBLANK_SUPPORTED, (uint8_t *)(&hblank_size),
+				sizeof(hblank_size));
 		}
-
 		DC_TRACE_LEVEL_MESSAGE(DAL_TRACE_LEVEL_INFORMATION,
 							WPP_BIT_FLAG_DC_DETECTION_DP_CAPS,
 							"result=%u link_index=%u enum dce_version=%d DPCD=0x%04X min_hblank=%u branch_dev_id=0x%x branch_dev_name='%c%c%c%c%c%c'",
diff --git a/drivers/gpu/drm/amd/display/dc/dc_dp_types.h b/drivers/gpu/drm/amd/display/dc/dc_dp_types.h
index 2c54b6e0498bf..296793d8b2bf2 100644
--- a/drivers/gpu/drm/amd/display/dc/dc_dp_types.h
+++ b/drivers/gpu/drm/amd/display/dc/dc_dp_types.h
@@ -149,7 +149,6 @@ struct dc_link_settings {
 	enum dc_link_spread link_spread;
 	bool use_link_rate_set;
 	uint8_t link_rate_set;
-	bool dpcd_source_device_specific_field_support;
 };
 
 union dc_dp_ffe_preset {
-- 
2.39.0