[RFC 02/20] drm/xe: Fix display runtime_pm handling

[Rodrigo Vivi]

i915's intel_runtime_pm_get_if_in_use actually calls the
pm_runtime_get_if_active() with ign_usage_count = false, but Xe
was erroneously calling it with true because of the mem_access cases.
This can lead to unbalanced references.

Let's use directly the 'if_in_use' function provided by linux/pm_runtime.

Also, already start this new function protected from the runtime
recursion, since runtime_pm will need to call for display functions
for a proper D3Cold flow.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
---
 .../gpu/drm/xe/compat-i915-headers/i915_drv.h   |  2 +-
 drivers/gpu/drm/xe/xe_pm.c                      | 17 +++++++++++++++++
 drivers/gpu/drm/xe/xe_pm.h                      |  1 +
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/compat-i915-headers/i915_drv.h b/drivers/gpu/drm/xe/compat-i915-headers/i915_drv.h
index 5d2a77b52db41..f0464dfc45cf5 100644
--- a/drivers/gpu/drm/xe/compat-i915-headers/i915_drv.h
+++ b/drivers/gpu/drm/xe/compat-i915-headers/i915_drv.h
@@ -177,7 +177,7 @@ static inline bool intel_runtime_pm_get_if_in_use(struct xe_runtime_pm *pm)
 {
 	struct xe_device *xe = container_of(pm, struct xe_device, runtime_pm);
 
-	return xe_pm_runtime_get_if_active(xe);
+	return xe_pm_runtime_get_if_in_use(xe);
 }
 
 static inline void intel_runtime_pm_put_unchecked(struct xe_runtime_pm *pm)
diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
index a7fe69d2f442e..5a4d601ab0976 100644
--- a/drivers/gpu/drm/xe/xe_pm.c
+++ b/drivers/gpu/drm/xe/xe_pm.c
@@ -400,6 +400,23 @@ int xe_pm_runtime_get_if_active(struct xe_device *xe)
 	return pm_runtime_get_if_active(xe->drm.dev, true);
 }
 
+/**
+ * xe_pm_runtime_get_if_in_use - Get a runtime_pm reference and resume if needed
+ * @xe: xe device instance
+ *
+ * Returns: True if device is awake and the the reference was taken, false otherwise.
+ */
+bool xe_pm_runtime_get_if_in_use(struct xe_device *xe)
+{
+	if (xe_pm_read_callback_task(xe) == current) {
+		/* The device is awake, grab the ref and move on */
+                pm_runtime_get_noresume(xe->drm.dev);
+		return true;
+	}
+
+        return pm_runtime_get_if_in_use(xe->drm.dev) >= 0;
+}
+
 /**
  * xe_pm_assert_unbounded_bridge - Disable PM on unbounded pcie parent bridge
  * @xe: xe device instance
diff --git a/drivers/gpu/drm/xe/xe_pm.h b/drivers/gpu/drm/xe/xe_pm.h
index 6b9031f7af243..13eebd604dd96 100644
--- a/drivers/gpu/drm/xe/xe_pm.h
+++ b/drivers/gpu/drm/xe/xe_pm.h
@@ -27,6 +27,7 @@ int xe_pm_runtime_resume(struct xe_device *xe);
 int xe_pm_runtime_get(struct xe_device *xe);
 int xe_pm_runtime_put(struct xe_device *xe);
 int xe_pm_runtime_get_if_active(struct xe_device *xe);
+bool xe_pm_runtime_get_if_in_use(struct xe_device *xe);
 void xe_pm_assert_unbounded_bridge(struct xe_device *xe);
 int xe_pm_set_vram_threshold(struct xe_device *xe, u32 threshold);
 void xe_pm_d3cold_allowed_toggle(struct xe_device *xe);
-- 
2.43.0