linux-kernel - [PATCH] drm/msm/dp: update is_connected status base on sink count at dp_pm

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Date:   Wed, 28 Jul 2021 14:30:54 -0700
From:   Kuogee Hsieh <khsieh@...eaurora.org>
To:     robdclark@...il.com, sean@...rly.run, swboyd@...omium.org,
        vkoul@...nel.org, agross@...nel.org, bjorn.andersson@...aro.org
Cc:     abhinavk@...eaurora.org, aravindh@...eaurora.org,
        khsieh@...eaurora.org, freedreno@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/msm/dp: update is_connected status base on sink count at dp_pm_resume()

Currently at dp_pm_resume() is_connected state is decided base on hpd connection
status only. This will put is_connected in wrongly "true" state at the scenario
that dongle attached to DUT but without hmdi cable connecting to it. Fix this
problem by adding read sink count from dongle and decided is_connected state base
on both sink count and hpd connection status.

Signed-off-by: Kuogee Hsieh <khsieh@...eaurora.org>
---
 drivers/gpu/drm/msm/dp/dp_display.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 2b660e9..9bcb261 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1308,6 +1308,17 @@ static int dp_display_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static int dp_get_sink_count(struct dp_display_private *dp)
+{
+	u8 sink_count;
+
+	sink_count = drm_dp_read_sink_count(dp->aux);
+	if (sink_count < 0)
+		return 0;
+
+	return sink_count;
+}
+
 static int dp_pm_resume(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
@@ -1327,14 +1338,22 @@ static int dp_pm_resume(struct device *dev)
 
 	dp_catalog_ctrl_hpd_config(dp->catalog);
 
-	status = dp_catalog_link_is_connected(dp->catalog);
+	/*
+	 * set sink to normal operation mode -- D0
+	 * before dpcd read
+	 */
+	dp_link_psm_config(dp->link, &dp->panel->link_info, false);
 
+	if ((status = dp_catalog_link_is_connected(dp->catalog)))
+		dp->link->sink_count = dp_get_sink_count(dp);
+	else
+		dp->link->sink_count = 0;
 	/*
 	 * 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)
+	if (dp->link->sink_count)
 		dp->dp_display.is_connected = true;
 	else
 		dp->dp_display.is_connected = false;
-- 
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