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

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Date:   Fri, 30 Oct 2020 16:23:10 -0700
From:   Kuogee Hsieh <khsieh@...eaurora.org>
To:     robdclark@...il.com, sean@...rly.run, swboyd@...omium.org
Cc:     tanmay@...eaurora.org, abhinavk@...eaurora.org,
        aravindh@...eaurora.org, khsieh@...eaurora.org,
        rnayak@...eaurora.org, airlied@...ux.ie, daniel@...ll.ch,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] 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.
Link rate read back from sink need to be convert into
really rate by timing 2.7Mb. For example 0x0A is equivalent
to 2.7Gb. This patch also convert link rate correctly to fix
phy compliance test link rate error.

Chanegs in V2:
-- revise commit 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 | 24 +++++++++++-------------
 2 files changed, 17 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index 904698dfc7f7..844ba756a2c6 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 = len;
 	}
 
-	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..64a002d100c7 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;
 }
@@ -943,20 +944,17 @@ 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);
+
+	bool clock_recovery_done = drm_dp_clock_recovery_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));
+			channel_eq_done, clock_recovery_done);
+
+	if (channel_eq_done && clock_recovery_done)
+		return -EINVAL;
 
 	return 0;
 }

base-commit: 03a9adc88c206b3857ce95f4f4d3b185d429fa31
-- 
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