Guard hardware register access in the threaded IRQ handler with
pm_runtime_get_if_active().

A possible ordering exists where the top-half IRQ handler returns
IRQ_WAKE_THREAD, runtime PM suspend powers down the VPU, and the
threaded IRQ handler subsequently runs and accesses hardware
registers through iris_vpu_clear_interrupt().

Avoid touching registers when the device is no longer active by
skipping interrupt processing when runtime PM indicates that the
device is suspended.

Signed-off-by: Hungyu Lin <dennylin0707@gmail.com>
---
v4:
- Clarify the possible ordering between IRQ_WAKE_THREAD,
  runtime PM suspend, and the threaded IRQ handler.
- Describe the race condition motivating the runtime PM check.

v3:
- Remove the early enable_irq() from the PM-inactive early-return path.
- IRQ re-enablement is already handled by iris_vpu_power_on() after power-on.

v2:
- Use pm_runtime_get_if_active() instead of pm_runtime_get_if_in_use().
- Handle negative runtime PM return values correctly.
- Return IRQ_NONE when interrupt processing is skipped.

 drivers/media/platform/qcom/iris/iris_hfi_common.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/media/platform/qcom/iris/iris_hfi_common.c b/drivers/media/platform/qcom/iris/iris_hfi_common.c
index 621c66593d88..ab2ec1e75309 100644
--- a/drivers/media/platform/qcom/iris/iris_hfi_common.c
+++ b/drivers/media/platform/qcom/iris/iris_hfi_common.c
@@ -100,10 +100,17 @@ irqreturn_t iris_hfi_isr(int irq, void *data)
 irqreturn_t iris_hfi_isr_handler(int irq, void *data)
 {
 	struct iris_core *core = data;
+	int ret;
 
 	if (!core)
 		return IRQ_NONE;
 
+	if (IS_ENABLED(CONFIG_PM)) {
+		ret = pm_runtime_get_if_active(core->dev);
+		if (ret <= 0)
+			return IRQ_NONE;
+	}
+
 	mutex_lock(&core->lock);
 	pm_runtime_mark_last_busy(core->dev);
 	iris_vpu_clear_interrupt(core);
@@ -111,6 +118,8 @@ irqreturn_t iris_hfi_isr_handler(int irq, void *data)
 
 	core->hfi_response_ops->hfi_response_handler(core);
 
+	pm_runtime_put_autosuspend(core->dev);
+
 	if (!iris_vpu_watchdog(core, core->intr_status))
 		enable_irq(irq);
 
-- 
2.34.1