[PATCH] drm/msm/dpu: ensure device suspend happens during PM sleep

[Kalyan Thota <kalyan_t@xxxxxxxxxxxxxx>]

"The PM core always increments the runtime usage counter
before calling the ->suspend() callback and decrements it
after calling the ->resume() callback"

DPU and DSI are managed as runtime devices. When
suspend is triggered, PM core adds a refcount on all the
devices and calls device suspend, since usage count is
already incremented, runtime suspend was not getting called
and it kept the clocks on which resulted in target not
entering into XO shutdown.

Add changes to force suspend on runtime devices during pm sleep.

Changes in v1:
 - Remove unnecessary checks in the function
    _dpu_kms_disable_dpu (Rob Clark).

Changes in v2:
 - Avoid using suspend_late to reset the usagecount
   as suspend_late might not be called during suspend
   call failures (Doug).

Changes in v3:
 - Use force suspend instead of managing device usage_count
   via runtime put and get API's to trigger callbacks (Doug).

Changes in v4:
 - Check the return values of pm_runtime_force_suspend and
   pm_runtime_force_resume API's and pass appropriately (Doug).

Signed-off-by: Kalyan Thota <kalyan_t@xxxxxxxxxxxxxx>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c |  2 ++
 drivers/gpu/drm/msm/dsi/dsi.c           |  2 ++
 drivers/gpu/drm/msm/msm_drv.c           | 14 +++++++++++++-
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
index ce19f1d..b886d9d 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
@@ -1123,6 +1123,8 @@ static int __maybe_unused dpu_runtime_resume(struct device *dev)
 
 static const struct dev_pm_ops dpu_pm_ops = {
 	SET_RUNTIME_PM_OPS(dpu_runtime_suspend, dpu_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
 };
 
 static const struct of_device_id dpu_dt_match[] = {
diff --git a/drivers/gpu/drm/msm/dsi/dsi.c b/drivers/gpu/drm/msm/dsi/dsi.c
index 55ea4bc2..62704885 100644
--- a/drivers/gpu/drm/msm/dsi/dsi.c
+++ b/drivers/gpu/drm/msm/dsi/dsi.c
@@ -161,6 +161,8 @@ static int dsi_dev_remove(struct platform_device *pdev)
 
 static const struct dev_pm_ops dsi_pm_ops = {
 	SET_RUNTIME_PM_OPS(msm_dsi_runtime_suspend, msm_dsi_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
 };
 
 static struct platform_driver dsi_driver = {
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index 7d985f8..4b93fc1 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -1040,6 +1040,7 @@ static int msm_pm_suspend(struct device *dev)
 {
 	struct drm_device *ddev = dev_get_drvdata(dev);
 	struct msm_drm_private *priv = ddev->dev_private;
+	int ret, rc;
 
 	if (WARN_ON(priv->pm_state))
 		drm_atomic_state_put(priv->pm_state);
@@ -1051,7 +1052,14 @@ static int msm_pm_suspend(struct device *dev)
 		return ret;
 	}
 
-	return 0;
+	ret = pm_runtime_force_suspend(dev);
+	if (ret) {
+		rc = drm_atomic_helper_resume(ddev, priv->pm_state);
+		if (!rc)
+			priv->pm_state = NULL;
+	}
+
+	return ret;
 }
 
 static int msm_pm_resume(struct device *dev)
@@ -1063,6 +1071,10 @@ static int msm_pm_resume(struct device *dev)
 	if (WARN_ON(!priv->pm_state))
 		return -ENOENT;
 
+	ret = pm_runtime_force_resume(dev);
+	if (ret)
+		return ret;
+
 	ret = drm_atomic_helper_resume(ddev, priv->pm_state);
 	if (!ret)
 		priv->pm_state = NULL;
-- 
1.9.1