linux-kernel - [PATCH v3 4/8] drm/msm/dp: Move link training to atomic

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Message-Id: <20260115-hpd-refactor-v3-4-08e2f3bcd2e0@oss.qualcomm.com>
Date: Thu, 15 Jan 2026 09:29:09 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Rob Clark <robin.clark@....qualcomm.com>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jesszhan0024@...il.com>, Sean Paul <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Kuogee Hsieh <quic_khsieh@...cinc.com>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Jessica Zhang <jessica.zhang@....qualcomm.com>
Subject: [PATCH v3 4/8] drm/msm/dp: Move link training to atomic_enable()

From: Jessica Zhang <jessica.zhang@....qualcomm.com>

Currently, the DP link training is being done during HPD. Move
link training to atomic_enable() in accordance with the atomic_enable()
documentation.

Link disabling is already done in atomic_post_disable() (as part of the
dp_ctrl_off_link_stream() helper).

Finally, call the plug/unplug handlers directly in hpd_notify() instead
of queueing them in the event thread so that they aren't preempted by
other events.

Signed-off-by: Jessica Zhang <jessica.zhang@....qualcomm.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
---
 drivers/gpu/drm/msm/dp/dp_display.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index a05144de3b93..3184066adb15 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -436,11 +436,6 @@ static int msm_dp_display_process_hpd_high(struct msm_dp_display_private *dp)
 	msm_dp_link_psm_config(dp->link, &dp->panel->link_info, false);
 
 	msm_dp_link_reset_phy_params_vx_px(dp->link);
-	rc = msm_dp_ctrl_on_link(dp->ctrl);
-	if (rc) {
-		DRM_ERROR("failed to complete DP link training\n");
-		goto end;
-	}
 
 	msm_dp_add_event(dp, EV_USER_NOTIFICATION, true, 0);
 
@@ -1695,6 +1690,12 @@ void msm_dp_bridge_atomic_enable(struct drm_bridge *drm_bridge,
 		force_link_train = true;
 	}
 
+	rc = msm_dp_ctrl_on_link(msm_dp_display->ctrl);
+	if (rc) {
+		DRM_ERROR("Failed link training (rc=%d)\n", rc);
+		drm_connector_set_link_status_property(dp->connector, DRM_LINK_STATUS_BAD);
+	}
+
 	msm_dp_display_enable(msm_dp_display, force_link_train);
 
 	rc = msm_dp_display_post_enable(dp);

-- 
2.47.3