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

"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).

Changes in v5:
 - With v4 patch, test cycle has uncovered issues in device resume.

   On bubs: cmd tx failures were seen as SW is sending panel off
   commands when the dsi resources are turned off.

   Upon suspend, DRM driver will issue a NULL composition to the
   dpu, followed by turning off all the HW blocks.

   v5 changes will serialize the NULL commit and resource unwinding
   by handling them under PM prepare and PM complete phases there by
   ensuring that clks are on when panel off commands are being
   processed.

Changes in v6:
- Use drm_mode_config_helper_suspend/resume() instead of legacy API
  drm_atomic_helper_suspend/resume() (Doug).

  Trigger runtime callbacks from the suspend/resume call to turn
  off the resources.

Changes in v7:
- Add "__maybe_unused" to the functions to avoid compilation
  failures. Cleanup unnecessary configs (Doug).

Signed-off-by: Kalyan Thota <kalyan_t@codeaurora.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c

@@ -1115,6 +1115,8 @@ 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[] = {

drivers/gpu/drm/msm/dsi/dsi.c

@@ -161,6 +161,8 @@ static const struct of_device_id dt_match[] = {
 
 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 = {

drivers/gpu/drm/msm/msm_drv.c

@@ -1039,75 +1039,70 @@ static struct drm_driver msm_driver = {
 	.patchlevel         = MSM_VERSION_PATCHLEVEL,
 };
 
-#ifdef CONFIG_PM_SLEEP
-static int msm_pm_suspend(struct device *dev)
+static int __maybe_unused msm_runtime_suspend(struct device *dev)
 {
 	struct drm_device *ddev = dev_get_drvdata(dev);
 	struct msm_drm_private *priv = ddev->dev_private;
+	struct msm_mdss *mdss = priv->mdss;
 
-	if (WARN_ON(priv->pm_state))
-		drm_atomic_state_put(priv->pm_state);
+	DBG("");
 
-	priv->pm_state = drm_atomic_helper_suspend(ddev);
-	if (IS_ERR(priv->pm_state)) {
-		int ret = PTR_ERR(priv->pm_state);
-		DRM_ERROR("Failed to suspend dpu, %d\n", ret);
-		return ret;
-	}
+	if (mdss && mdss->funcs)
+		return mdss->funcs->disable(mdss);
 
 	return 0;
 }
 
-static int msm_pm_resume(struct device *dev)
+static int __maybe_unused msm_runtime_resume(struct device *dev)
 {
 	struct drm_device *ddev = dev_get_drvdata(dev);
 	struct msm_drm_private *priv = ddev->dev_private;
-	int ret;
+	struct msm_mdss *mdss = priv->mdss;
 
-	if (WARN_ON(!priv->pm_state))
-		return -ENOENT;
+	DBG("");
 
-	ret = drm_atomic_helper_resume(ddev, priv->pm_state);
-	if (!ret)
-		priv->pm_state = NULL;
+	if (mdss && mdss->funcs)
+		return mdss->funcs->enable(mdss);
 
-	return ret;
+	return 0;
 }
-#endif
 
-#ifdef CONFIG_PM
-static int msm_runtime_suspend(struct device *dev)
+static int __maybe_unused msm_pm_suspend(struct device *dev)
 {
-	struct drm_device *ddev = dev_get_drvdata(dev);
-	struct msm_drm_private *priv = ddev->dev_private;
-	struct msm_mdss *mdss = priv->mdss;
 
-	DBG("");
+	if (pm_runtime_suspended(dev))
+		return 0;
 
-	if (mdss && mdss->funcs)
-		return mdss->funcs->disable(mdss);
+	return msm_runtime_suspend(dev);
+}
 
-	return 0;
+static int __maybe_unused msm_pm_resume(struct device *dev)
+{
+	if (pm_runtime_suspended(dev))
+		return 0;
+
+	return msm_runtime_resume(dev);
 }
 
-static int msm_runtime_resume(struct device *dev)
+static int __maybe_unused msm_pm_prepare(struct device *dev)
 {
 	struct drm_device *ddev = dev_get_drvdata(dev);
-	struct msm_drm_private *priv = ddev->dev_private;
-	struct msm_mdss *mdss = priv->mdss;
 
-	DBG("");
+	return drm_mode_config_helper_suspend(ddev);
+}
 
-	if (mdss && mdss->funcs)
-		return mdss->funcs->enable(mdss);
+static void __maybe_unused msm_pm_complete(struct device *dev)
+{
+	struct drm_device *ddev = dev_get_drvdata(dev);
 
-	return 0;
+	drm_mode_config_helper_resume(ddev);
 }
-#endif
 
 static const struct dev_pm_ops msm_pm_ops = {
 	SET_SYSTEM_SLEEP_PM_OPS(msm_pm_suspend, msm_pm_resume)
 	SET_RUNTIME_PM_OPS(msm_runtime_suspend, msm_runtime_resume, NULL)
+	.prepare = msm_pm_prepare,
+	.complete = msm_pm_complete,
 };
 
 /*