linux-kernel - [PATCH 5.12 344/363] drm/msm/dp: check sink_count before update is

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Message-Id: <20210517140314.235086456@linuxfoundation.org>
Date:   Mon, 17 May 2021 16:03:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Stephen Boyd <swboyd@...omium.org>,
        Kuogee Hsieh <khsieh@...eaurora.org>,
        Rob Clark <robdclark@...omium.org>
Subject: [PATCH 5.12 344/363] drm/msm/dp: check sink_count before update is_connected status

From: Kuogee Hsieh <khsieh@...eaurora.org>

commit d9aa6571b28ba0022de1e48801ff03a1854c7ef2 upstream.

Link status is different from display connected status in the case
of something like an Apple dongle where the type-c plug can be
connected, and therefore the link is connected, but no sink is
connected until an HDMI cable is plugged into the dongle.
The sink_count of DPCD of dongle will increase to 1 once an HDMI
cable is plugged into the dongle so that display connected status
will become true. This checking also apply at pm_resume.

Changes in v4:
-- none

Fixes: 94e58e2d06e3 ("drm/msm/dp: reset dp controller only at boot up and pm_resume")
Reported-by: Stephen Boyd <swboyd@...omium.org>
Reviewed-by: Stephen Boyd <swboyd@...omium.org>
Tested-by: Stephen Boyd <swboyd@...omium.org>
Signed-off-by: Kuogee Hsieh <khsieh@...eaurora.org>
Fixes: 8ede2ecc3e5e ("drm/msm/dp: Add DP compliance tests on Snapdragon Chipsets")
Link: https://lore.kernel.org/r/1619048258-8717-2-git-send-email-khsieh@codeaurora.org
Signed-off-by: Rob Clark <robdclark@...omium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/msm/dp/dp_display.c |   15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -595,10 +595,8 @@ static int dp_connect_pending_timeout(st
 	mutex_lock(&dp->event_mutex);
 
 	state = dp->hpd_state;
-	if (state == ST_CONNECT_PENDING) {
-		dp_display_enable(dp, 0);
+	if (state == ST_CONNECT_PENDING)
 		dp->hpd_state = ST_CONNECTED;
-	}
 
 	mutex_unlock(&dp->event_mutex);
 
@@ -677,10 +675,8 @@ static int dp_disconnect_pending_timeout
 	mutex_lock(&dp->event_mutex);
 
 	state =  dp->hpd_state;
-	if (state == ST_DISCONNECT_PENDING) {
-		dp_display_disable(dp, 0);
+	if (state == ST_DISCONNECT_PENDING)
 		dp->hpd_state = ST_DISCONNECTED;
-	}
 
 	mutex_unlock(&dp->event_mutex);
 
@@ -1279,7 +1275,12 @@ static int dp_pm_resume(struct device *d
 
 	status = dp_catalog_link_is_connected(dp->catalog);
 
-	if (status)
+	/*
+	 * can not declared display is connected unless
+	 * HDMI cable is plugged in and sink_count of
+	 * dongle become 1
+	 */
+	if (status && dp->link->sink_count)
 		dp->dp_display.is_connected = true;
 	else
 		dp->dp_display.is_connected = false;