[RFC PATCH 16/18] drm/panthor: Synchronize HW component PM transitions

[Karunika Choo]

Split hardware component suspend/resume from the top-level device PM
path and protect those transitions with a dedicated mutex and state
flag.

This lets access-window arbitration suspend or resume GPU components
while runtime PM state remains controlled by the outer PM path.

Signed-off-by: Karunika Choo <karunika.choo@xxxxxxx>
---
 drivers/gpu/drm/panthor/panthor_aw.c     |  1 -
 drivers/gpu/drm/panthor/panthor_device.c | 50 +++++++++++++++++++++---
 drivers/gpu/drm/panthor/panthor_device.h |  9 +++++
 3 files changed, 53 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_aw.c b/drivers/gpu/drm/panthor/panthor_aw.c
index 00a52175f3a3..146907a3098d 100644
--- a/drivers/gpu/drm/panthor/panthor_aw.c
+++ b/drivers/gpu/drm/panthor/panthor_aw.c
@@ -192,7 +192,6 @@ static void panthor_aw_handle_message(struct panthor_aw *aw)
 		drm_warn(&ptdev->base, "Unsupported msg id (0x%x)", msg_id);
 }
 
-
 static irqreturn_t panthor_aw_irq_raw_hander(int irq, void *data)
 {
 	struct panthor_irq *pirq = data;
diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
index 7248e2aa9da2..a8aedbee7c97 100644
--- a/drivers/gpu/drm/panthor/panthor_device.c
+++ b/drivers/gpu/drm/panthor/panthor_device.c
@@ -179,6 +179,10 @@ int panthor_device_init(struct panthor_device *ptdev)
 	if (ret)
 		return ret;
 
+	ret = drmm_mutex_init(&ptdev->base, &ptdev->pm.hw_component_lock);
+	if (ret)
+		return ret;
+
 	ret = drmm_mutex_init(&ptdev->base, &ptdev->pm.mmio_lock);
 	if (ret)
 		return ret;
@@ -289,6 +293,9 @@ int panthor_device_init(struct panthor_device *ptdev)
 	if (ret)
 		goto err_unplug_mmu;
 
+	atomic_set(&ptdev->pm.hw_component_state,
+		   PANTHOR_DEVICE_PM_STATE_ACTIVE);
+
 	ret = panthor_sched_init(ptdev);
 	if (ret)
 		goto err_unplug_fw;
@@ -477,21 +484,55 @@ int panthor_device_mmap_io(struct panthor_device *ptdev, struct vm_area_struct *
 	return 0;
 }
 
-static int panthor_device_resume_hw_components(struct panthor_device *ptdev)
+int panthor_device_suspend_hw_components(struct panthor_device *ptdev)
+{
+	guard(mutex)(&ptdev->pm.hw_component_lock);
+
+	if (atomic_read(&ptdev->pm.hw_component_state) ==
+	    PANTHOR_DEVICE_PM_STATE_SUSPENDED)
+		return 0;
+
+	if (!pm_runtime_suspended(ptdev->base.dev)) {
+		panthor_fw_suspend(ptdev);
+		panthor_mmu_suspend(ptdev);
+		panthor_gpu_suspend(ptdev);
+		panthor_pwr_suspend(ptdev);
+	}
+
+	atomic_set(&ptdev->pm.hw_component_state,
+		   PANTHOR_DEVICE_PM_STATE_SUSPENDED);
+
+	return 0;
+}
+
+int panthor_device_resume_hw_components(struct panthor_device *ptdev)
 {
 	int ret;
 
+	guard(mutex)(&ptdev->pm.hw_component_lock);
+
+	if (atomic_read(&ptdev->pm.hw_component_state) ==
+	    PANTHOR_DEVICE_PM_STATE_ACTIVE)
+		return 0;
+
 	panthor_pwr_resume(ptdev);
 	panthor_gpu_resume(ptdev);
 	panthor_mmu_resume(ptdev);
 
 	ret = panthor_fw_resume(ptdev);
-	if (!ret)
+	if (!ret) {
+		atomic_set(&ptdev->pm.hw_component_state,
+			   PANTHOR_DEVICE_PM_STATE_ACTIVE);
 		return 0;
+	}
 
 	panthor_mmu_suspend(ptdev);
 	panthor_gpu_suspend(ptdev);
 	panthor_pwr_suspend(ptdev);
+
+	atomic_set(&ptdev->pm.hw_component_state,
+		   PANTHOR_DEVICE_PM_STATE_SUSPENDED);
+
 	return ret;
 }
 
@@ -602,10 +643,7 @@ int panthor_device_suspend(struct device *dev)
 		 * The end of the reset will happen in the resume path though.
 		 */
 		panthor_sched_suspend(ptdev);
-		panthor_fw_suspend(ptdev);
-		panthor_mmu_suspend(ptdev);
-		panthor_gpu_suspend(ptdev);
-		panthor_pwr_suspend(ptdev);
+		panthor_device_suspend_hw_components(ptdev);
 		drm_dev_exit(cookie);
 	}
 
diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
index a1092d02a1fe..d7beb7165577 100644
--- a/drivers/gpu/drm/panthor/panthor_device.h
+++ b/drivers/gpu/drm/panthor/panthor_device.h
@@ -350,6 +350,12 @@ struct panthor_device {
 
 		/** @recovery_needed: True when a resume attempt failed. */
 		atomic_t recovery_needed;
+
+		/** @hw_component_lock: Lock protects HW component PM state transitions */
+		struct mutex hw_component_lock;
+
+		/** @hw_component_state: HW component PM state */
+		atomic_t hw_component_state;
 	} pm;
 
 	/** @profile_mask: User-set profiling flags for job accounting. */
@@ -439,6 +445,9 @@ int panthor_device_mmap_io(struct panthor_device *ptdev,
 int panthor_device_resume(struct device *dev);
 int panthor_device_suspend(struct device *dev);
 
+int panthor_device_suspend_hw_components(struct panthor_device *ptdev);
+int panthor_device_resume_hw_components(struct panthor_device *ptdev);
+
 static inline int panthor_device_resume_and_get(struct panthor_device *ptdev)
 {
 	int ret = pm_runtime_resume_and_get(ptdev->base.dev);
-- 
2.43.0