linux-kernel - [PATCH v2 2/3] drm/msm/dp: skip checking LINK_STATUS

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Message-Id: <20201113220803.15033-3-khsieh@codeaurora.org>
Date:   Fri, 13 Nov 2020 14:08:02 -0800
From:   Kuogee Hsieh <khsieh@...eaurora.org>
To:     dri-devel@...ts.freedesktop.org, robdclark@...il.com,
        sean@...rly.run, swboyd@...omium.org
Cc:     Kuogee Hsieh <khsieh@...eaurora.org>, tanmay@...eaurora.org,
        abhinavk@...eaurora.org, aravindh@...eaurora.org, airlied@...ux.ie,
        daniel@...ll.ch, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/3] drm/msm/dp: skip checking LINK_STATUS_UPDATED bit

Some dongle will not clear LINK_STATUS_UPDATED bit after
DPCD read which cause link training failed. This patch
just read 6 bytes of DPCD link status from sink and return
without checking LINK_STATUS_UPDATED bit.
Only 8 bits are used to represent link rate at sinker DPCD.
The really link rate is 2.7Mb times the 8 bits value.
For example, 0x0A at DPCD is equal to 2.7Gb (10 * 2.7Mb).
This patch also convert 8 bits value of DPCD to really link
rate to fix worng link rate error during phy compliance test.

Changes in V2:
--  fix Fixes tag text

Fixes: fd4a29bed29b ("drm/msm/dp: DisplayPort PHY compliance tests fixup")
Signed-off-by: Kuogee Hsieh <khsieh@...eaurora.org>
---
 drivers/gpu/drm/msm/dp/dp_ctrl.c | 20 ++++++--------------
 drivers/gpu/drm/msm/dp/dp_link.c | 29 ++++++++++++++---------------
 2 files changed, 20 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index c7af040ce252..b9ca844ce2ad 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1061,23 +1061,15 @@ static bool dp_ctrl_train_pattern_set(struct dp_ctrl_private *ctrl,
 static int dp_ctrl_read_link_status(struct dp_ctrl_private *ctrl,
 				    u8 *link_status)
 {
-	int len = 0;
-	u32 const offset = DP_LANE_ALIGN_STATUS_UPDATED - DP_LANE0_1_STATUS;
-	u32 link_status_read_max_retries = 100;
-
-	while (--link_status_read_max_retries) {
-		len = drm_dp_dpcd_read_link_status(ctrl->aux,
-			link_status);
-		if (len != DP_LINK_STATUS_SIZE) {
-			DRM_ERROR("DP link status read failed, err: %d\n", len);
-			return len;
-		}
+	int ret = 0, len;
 
-		if (!(link_status[offset] & DP_LINK_STATUS_UPDATED))
-			return 0;
+	len = drm_dp_dpcd_read_link_status(ctrl->aux, link_status);
+	if (len != DP_LINK_STATUS_SIZE) {
+		DRM_ERROR("DP link status read failed, err: %d\n", len);
+		ret = -EINVAL;
 	}
 
-	return -ETIMEDOUT;
+	return ret;
 }
 
 static int dp_ctrl_link_train_1(struct dp_ctrl_private *ctrl,
diff --git a/drivers/gpu/drm/msm/dp/dp_link.c b/drivers/gpu/drm/msm/dp/dp_link.c
index 49d7fad36fc4..be986da78c4a 100644
--- a/drivers/gpu/drm/msm/dp/dp_link.c
+++ b/drivers/gpu/drm/msm/dp/dp_link.c
@@ -773,7 +773,8 @@ static int dp_link_process_link_training_request(struct dp_link_private *link)
 			link->request.test_lane_count);
 
 	link->dp_link.link_params.num_lanes = link->request.test_lane_count;
-	link->dp_link.link_params.rate = link->request.test_link_rate;
+	link->dp_link.link_params.rate = 
+		drm_dp_bw_code_to_link_rate(link->request.test_link_rate);
 
 	return 0;
 }
@@ -943,22 +944,20 @@ static u8 get_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r)
  */
 static int dp_link_process_link_status_update(struct dp_link_private *link)
 {
-	if (!(get_link_status(link->link_status,
-				DP_LANE_ALIGN_STATUS_UPDATED) &
-				DP_LINK_STATUS_UPDATED) ||
-			(drm_dp_clock_recovery_ok(link->link_status,
-					link->dp_link.link_params.num_lanes) &&
-			drm_dp_channel_eq_ok(link->link_status,
-					link->dp_link.link_params.num_lanes)))
-		return -EINVAL;
+       bool channel_eq_done = drm_dp_channel_eq_ok(link->link_status,
+                       link->dp_link.link_params.num_lanes);
 
-	DRM_DEBUG_DP("channel_eq_done = %d, clock_recovery_done = %d\n",
-			drm_dp_clock_recovery_ok(link->link_status,
-			link->dp_link.link_params.num_lanes),
-			drm_dp_clock_recovery_ok(link->link_status,
-			link->dp_link.link_params.num_lanes));
+       bool clock_recovery_done = drm_dp_clock_recovery_ok(link->link_status,
+                       link->dp_link.link_params.num_lanes);
 
-	return 0;
+       DRM_DEBUG_DP("channel_eq_done = %d, clock_recovery_done = %d\n",
+                        channel_eq_done, clock_recovery_done);
+
+       if (channel_eq_done && clock_recovery_done)
+               return -EINVAL;
+
+
+       return 0;
 }
 
 /**
-- 
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