[Intel-gfx] [PATCH 19/19] drm/i915: Sync against the GuC log buffer flush work item on system suspend

[akash.goel at intel.com]

From: Akash Goel <akash.goel at intel.com>

The GuC log buffer flush work item does a register access to send the ack
to GuC and this work item, if not synced before suspend, can potentially
get executed after the GFX device is suspended.
The work item function uses rpm_get/rpm_put calls around the Hw access,
this covers the runtime suspend case but for system suspend case (which can
be done asychronously/forcefully) sync would be required as kernel can
potentially schedule the work items even after some devices, including GFX,
have been put to suspend.
Also sync has to be done conditionally i.e. only for the system suspend
case, as sync along with rpm_get/rpm_put calls can cause a deadlock for rpm
suspend path.

Cc: Imre Deak <imre.deak at intel.com>
Signed-off-by: Akash Goel <akash.goel at intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c            | 4 ++--
 drivers/gpu/drm/i915/i915_guc_submission.c | 8 +++++++-
 drivers/gpu/drm/i915/intel_guc.h           | 2 +-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index cdee60b..2ae0ad4 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1427,7 +1427,7 @@ static int i915_drm_suspend(struct drm_device *dev)
 		goto out;
 	}
 
-	intel_guc_suspend(dev);
+	intel_guc_suspend(dev, false);
 
 	intel_display_suspend(dev);
 
@@ -2321,7 +2321,7 @@ static int intel_runtime_suspend(struct device *device)
 	i915_gem_release_all_mmaps(dev_priv);
 	mutex_unlock(&dev->struct_mutex);
 
-	intel_guc_suspend(dev);
+	intel_guc_suspend(dev, true);
 
 	intel_runtime_pm_disable_interrupts(dev_priv);
 
diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index ef0c116..1af8a8b 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -1519,7 +1519,7 @@ void i915_guc_submission_fini(struct drm_i915_private *dev_priv)
  * intel_guc_suspend() - notify GuC entering suspend state
  * @dev:	drm device
  */
-int intel_guc_suspend(struct drm_device *dev)
+int intel_guc_suspend(struct drm_device *dev, bool rpm_suspend)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
 	struct intel_guc *guc = &dev_priv->guc;
@@ -1530,6 +1530,12 @@ int intel_guc_suspend(struct drm_device *dev)
 		return 0;
 
 	gen9_disable_guc_interrupts(dev_priv);
+	/* Sync is needed only for the system suspend case, runtime suspend
+	 * case is covered due to rpm get/put calls used around Hw access in
+	 * the work item function.
+	 */
+	if (!rpm_suspend && (i915.guc_log_level >= 0))
+		flush_work(&dev_priv->guc.log.flush_work);
 
 	ctx = dev_priv->kernel_context;
 
diff --git a/drivers/gpu/drm/i915/intel_guc.h b/drivers/gpu/drm/i915/intel_guc.h
index b56fe24..1367314 100644
--- a/drivers/gpu/drm/i915/intel_guc.h
+++ b/drivers/gpu/drm/i915/intel_guc.h
@@ -172,7 +172,7 @@ extern void intel_guc_init(struct drm_device *dev);
 extern int intel_guc_setup(struct drm_device *dev);
 extern void intel_guc_fini(struct drm_device *dev);
 extern const char *intel_guc_fw_status_repr(enum intel_guc_fw_status status);
-extern int intel_guc_suspend(struct drm_device *dev);
+extern int intel_guc_suspend(struct drm_device *dev, bool rpm_suspend);
 extern int intel_guc_resume(struct drm_device *dev);
 
 /* i915_guc_submission.c */
-- 
1.9.2