linux-kernel - [PATCH v2] drm/msm/dp: force link training for display resolution change

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Message-ID: <1653606555-18675-1-git-send-email-quic_khsieh@quicinc.com>
Date:   Thu, 26 May 2022 16:09:15 -0700
From:   Kuogee Hsieh <quic_khsieh@...cinc.com>
To:     <robdclark@...il.com>, <sean@...rly.run>, <swboyd@...omium.org>,
        <dianders@...omium.org>, <vkoul@...nel.org>, <daniel@...ll.ch>,
        <airlied@...ux.ie>, <agross@...nel.org>,
        <dmitry.baryshkov@...aro.org>, <bjorn.andersson@...aro.org>
CC:     <quic_abhinavk@...cinc.com>, <quic_aravindh@...cinc.com>,
        <quic_khsieh@...cinc.com>, <quic_sbillaka@...cinc.com>,
        <freedreno@...ts.freedesktop.org>,
        <dri-devel@...ts.freedesktop.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] drm/msm/dp: force link training for display resolution change

During display resolution changes display have to be disabled first
followed by display enable with new resolution. This patch force
main link always be retrained during display enable procedure to
simplify implementation instead of manually kicking of irq_hpd
handle.

Changes in v2:
-- set force_link_train flag on DP only (is_edp == false)

Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
---
 drivers/gpu/drm/msm/dp/dp_ctrl.c    |  6 +++---
 drivers/gpu/drm/msm/dp/dp_ctrl.h    |  2 +-
 drivers/gpu/drm/msm/dp/dp_display.c | 15 ++++++++-------
 3 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index af7a80c..ac226f5 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1551,7 +1551,7 @@ static int dp_ctrl_process_phy_test_request(struct dp_ctrl_private *ctrl)
 
 	ret = dp_ctrl_on_link(&ctrl->dp_ctrl);
 	if (!ret)
-		ret = dp_ctrl_on_stream(&ctrl->dp_ctrl);
+		ret = dp_ctrl_on_stream(&ctrl->dp_ctrl, false);
 	else
 		DRM_ERROR("failed to enable DP link controller\n");
 
@@ -1807,7 +1807,7 @@ static int dp_ctrl_link_retrain(struct dp_ctrl_private *ctrl)
 	return dp_ctrl_setup_main_link(ctrl, &training_step);
 }
 
-int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl)
+int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl, bool force_link_train)
 {
 	int ret = 0;
 	bool mainlink_ready = false;
@@ -1848,7 +1848,7 @@ int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl)
 		return 0;
 	}
 
-	if (!dp_ctrl_channel_eq_ok(ctrl))
+	if (force_link_tarin || !dp_ctrl_channel_eq_ok(ctrl))
 		dp_ctrl_link_retrain(ctrl);
 
 	/* stop txing train pattern to end link training */
diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.h b/drivers/gpu/drm/msm/dp/dp_ctrl.h
index 0745fde..b563e2e 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.h
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.h
@@ -21,7 +21,7 @@ struct dp_ctrl {
 };
 
 int dp_ctrl_on_link(struct dp_ctrl *dp_ctrl);
-int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl);
+int dp_ctrl_on_stream(struct dp_ctrl *dp_ctrl, bool force_link_train);
 int dp_ctrl_off_link_stream(struct dp_ctrl *dp_ctrl);
 int dp_ctrl_off_link(struct dp_ctrl *dp_ctrl);
 int dp_ctrl_off(struct dp_ctrl *dp_ctrl);
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index c388323..370348d 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -872,7 +872,7 @@ static int dp_display_enable(struct dp_display_private *dp, u32 data)
 		return 0;
 	}
 
-	rc = dp_ctrl_on_stream(dp->ctrl);
+	rc = dp_ctrl_on_stream(dp->ctrl, data);
 	if (!rc)
 		dp_display->power_on = true;
 
@@ -1654,6 +1654,7 @@ void dp_bridge_enable(struct drm_bridge *drm_bridge)
 	int rc = 0;
 	struct dp_display_private *dp_display;
 	u32 state;
+	bool force_link_train = false;
 
 	dp_display = container_of(dp, struct dp_display_private, dp_display);
 	if (!dp_display->dp_mode.drm_mode.clock) {
@@ -1688,10 +1689,14 @@ void dp_bridge_enable(struct drm_bridge *drm_bridge)
 
 	state =  dp_display->hpd_state;
 
-	if (state == ST_DISPLAY_OFF)
+	if (state == ST_DISPLAY_OFF) {
 		dp_display_host_phy_init(dp_display);
 
-	dp_display_enable(dp_display, 0);
+		if (!dp->is_edp)
+			force_link_train = true;
+	}
+
+	dp_display_enable(dp_display, force_link_train);
 
 	rc = dp_display_post_enable(dp);
 	if (rc) {
@@ -1700,10 +1705,6 @@ void dp_bridge_enable(struct drm_bridge *drm_bridge)
 		dp_display_unprepare(dp);
 	}
 
-	/* manual kick off plug event to train link */
-	if (state == ST_DISPLAY_OFF)
-		dp_add_event(dp_display, EV_IRQ_HPD_INT, 0, 0);
-
 	/* completed connection */
 	dp_display->hpd_state = ST_CONNECTED;
 
-- 
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