[PATCH v3] drm/msm/dp: check core_initialized flag at both host_init() and host_deinit()

[Kuogee Hsieh]

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()

Changes in v3:
-- re arrange to avoid commit text line over 75 chars

Fixes: 989ebe7bc446 ("drm/msm/dp: do not initialize phy until plugin interrupt received")
Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
---
 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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