[PATCH 2/2] media: cadence: csi2rx: disable error IRQ while runtime suspended

[Myeonghun Pak]

The error IRQ handler accesses MMIO while runtime suspend can disable
its clocks without draining the handler.

Request the IRQ with IRQF_NO_AUTOEN, enable it after successful runtime
resume, and disable and drain it before runtime suspend gates clocks.

This issue was identified during our ongoing static-analysis research
while reviewing kernel code.

Fixes: c85d3d5362a8 ("media: cadence: csi2rx: Support runtime PM")
Assisted-by: LLM
Cc: stable@xxxxxxxxxxxxxxx
Co-developed-by: Ijae Kim <ae878000@xxxxxxxxx>
Signed-off-by: Ijae Kim <ae878000@xxxxxxxxx>
Signed-off-by: Myeonghun Pak <mhun512@xxxxxxxxx>
---
 drivers/media/platform/cadence/cdns-csi2rx.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
index f8c626e19aa84569737aa785a31a0f8c94087613..9bb776b5a4c8248a65df733e3a8963a6393f0996 100644
--- a/drivers/media/platform/cadence/cdns-csi2rx.c
+++ b/drivers/media/platform/cadence/cdns-csi2rx.c
@@ -982,7 +982,7 @@ static int csi2rx_probe(struct platform_device *pdev)
 		dev_dbg(csi2rx->dev, "Optional interrupt not defined, proceeding without it\n");
 	} else {
 		ret = devm_request_irq(csi2rx->dev, csi2rx->error_irq,
-				       csi2rx_irq_handler, 0,
+				       csi2rx_irq_handler, IRQF_NO_AUTOEN,
 				       dev_name(&pdev->dev), csi2rx);
 		if (ret) {
 			dev_err(csi2rx->dev,
@@ -1042,6 +1042,10 @@ static int csi2rx_runtime_suspend(struct device *dev)
 {
 	struct csi2rx_priv *csi2rx = dev_get_drvdata(dev);
 
+	/* Drain the handler before disabling the clocks it needs. */
+	if (csi2rx->error_irq >= 0)
+		disable_irq(csi2rx->error_irq);
+
 	reset_control_assert(csi2rx->sys_rst);
 	clk_disable_unprepare(csi2rx->sys_clk);
 
@@ -1082,6 +1086,9 @@ static int csi2rx_runtime_resume(struct device *dev)
 
 	reset_control_deassert(csi2rx->sys_rst);
 
+	if (csi2rx->error_irq >= 0)
+		enable_irq(csi2rx->error_irq);
+
 	return 0;
 
 err_disable_pixclk: