linux-kernel - [PATCH v2] drm/msm/dp: check core_initialized flag at both host_init() and host

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Message-ID: <1677531877-10849-1-git-send-email-quic_khsieh@quicinc.com>
Date:   Mon, 27 Feb 2023 13:04:37 -0800
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@...il.com>, <agross@...nel.org>,
        <dmitry.baryshkov@...aro.org>, <andersson@...nel.org>
CC:     <quic_abhinavk@...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: check core_initialized flag at both host_init() and host_deinit()

There is a reboot/suspend test case where system suspend is forced during
system booting up. Since dp_display_host_init() of external DP is executed
at hpd thread context, this test case may created a scenario that
dp_display_host_deinit() from pm_suspend() run before dp_display_host_init()
if hpd thread has no chance to run during booting up while suspend request
command was issued. At this scenario system will crash at aux register
access at dp_display_host_deinit() since aux clock had not yet been enabled
by dp_display_host_init().  Therefore we have to ensure aux clock enabled
by checking core_initialized flag before access aux registers at pm_suspend.

Changes in v2:
-- at commit text, dp_display_host_init() instead of host_init()
-- at commit text, dp_display_host_deinit() instead of host_deinit()

Fixes: 989ebe7bc446 ("drm/msm/dp: do not initialize phy until plugin interrupt received")
Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
Reviewed-by: Stephen Boyd <swboyd@...omium.org>
---
 drivers/gpu/drm/msm/dp/dp_display.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index bde1a7c..1850738 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -460,10 +460,12 @@ static void dp_display_host_init(struct dp_display_private *dp)
 		dp->dp_display.connector_type, dp->core_initialized,
 		dp->phy_initialized);
 
-	dp_power_init(dp->power, false);
-	dp_ctrl_reset_irq_ctrl(dp->ctrl, true);
-	dp_aux_init(dp->aux);
-	dp->core_initialized = true;
+	if (!dp->core_initialized) {
+		dp_power_init(dp->power, false);
+		dp_ctrl_reset_irq_ctrl(dp->ctrl, true);
+		dp_aux_init(dp->aux);
+		dp->core_initialized = true;
+	}
 }
 
 static void dp_display_host_deinit(struct dp_display_private *dp)
@@ -472,10 +474,12 @@ static void dp_display_host_deinit(struct dp_display_private *dp)
 		dp->dp_display.connector_type, dp->core_initialized,
 		dp->phy_initialized);
 
-	dp_ctrl_reset_irq_ctrl(dp->ctrl, false);
-	dp_aux_deinit(dp->aux);
-	dp_power_deinit(dp->power);
-	dp->core_initialized = false;
+	if (dp->core_initialized) {
+		dp_ctrl_reset_irq_ctrl(dp->ctrl, false);
+		dp_aux_deinit(dp->aux);
+		dp_power_deinit(dp->power);
+		dp->core_initialized = false;
+	}
 }
 
 static int dp_display_usbpd_configure_cb(struct device *dev)
-- 
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