[PATCH v4 03/10] media: microchip-isc: synchronize the IRQ before disabling clocks on stop

isc_stop_streaming() masks the DMA interrupt and then drops the runtime
PM reference, which disables the ISC clocks. microchip_isc_interrupt()
may still be executing on another CPU at that point; it reads ISC_INTSR
over regmap, and touching the unclocked registers triggers an external
abort.

Store the IRQ number at probe and call synchronize_irq() after masking
the interrupt, before dropping the PM reference.

Fixes: 106267444f12 ("[media] atmel-isc: add the Image Sensor Controller code")
Cc: [email protected]
Signed-off-by: Balakrishnan Sambath <[email protected]>
Reviewed-by: Eugen Hristev <[email protected]>
---
 drivers/media/platform/microchip/microchip-isc-base.c    | 3 +++
 drivers/media/platform/microchip/microchip-isc.h         | 1 +
 drivers/media/platform/microchip/microchip-sama5d2-isc.c | 2 ++
 drivers/media/platform/microchip/microchip-sama7g5-isc.c | 2 ++
 4 files changed, 8 insertions(+)

diff --git a/drivers/media/platform/microchip/microchip-isc-base.c b/drivers/media/platform/microchip/microchip-isc-base.c
index ca4f3b5f58aa..debbc38717de 100644
--- a/drivers/media/platform/microchip/microchip-isc-base.c
+++ b/drivers/media/platform/microchip/microchip-isc-base.c
@@ -425,6 +425,9 @@ static void isc_stop_streaming(struct vb2_queue *vq)
 	/* Disable DMA interrupt */
 	regmap_write(isc->regmap, ISC_INTDIS, ISC_INT_DDONE);
 
+	/* let a running IRQ handler finish before the clock is disabled */
+	synchronize_irq(isc->irq);
+
 	pm_runtime_put_sync(isc->dev);
 
 	/* Disable stream on the sub device */
diff --git a/drivers/media/platform/microchip/microchip-isc.h b/drivers/media/platform/microchip/microchip-isc.h
index ad4e98a1dd8f..f5e322c2e36b 100644
--- a/drivers/media/platform/microchip/microchip-isc.h
+++ b/drivers/media/platform/microchip/microchip-isc.h
@@ -287,6 +287,7 @@ struct isc_device {
 	u32			dcfg;
 
 	struct device		*dev;
+	int			irq;
 	struct v4l2_device	v4l2_dev;
 	struct video_device	video_dev;
 
diff --git a/drivers/media/platform/microchip/microchip-sama5d2-isc.c b/drivers/media/platform/microchip/microchip-sama5d2-isc.c
index 532f2b50e2ea..fa06b272b25d 100644
--- a/drivers/media/platform/microchip/microchip-sama5d2-isc.c
+++ b/drivers/media/platform/microchip/microchip-sama5d2-isc.c
@@ -447,6 +447,8 @@ static int microchip_isc_probe(struct platform_device *pdev)
 	if (irq < 0)
 		return irq;
 
+	isc->irq = irq;
+
 	ret = devm_request_irq(dev, irq, microchip_isc_interrupt, 0,
 			       "microchip-sama5d2-isc", isc);
 	if (ret < 0) {
diff --git a/drivers/media/platform/microchip/microchip-sama7g5-isc.c b/drivers/media/platform/microchip/microchip-sama7g5-isc.c
index 0b72a61b51ee..eef4d0f4c520 100644
--- a/drivers/media/platform/microchip/microchip-sama7g5-isc.c
+++ b/drivers/media/platform/microchip/microchip-sama7g5-isc.c
@@ -436,6 +436,8 @@ static int microchip_xisc_probe(struct platform_device *pdev)
 	if (irq < 0)
 		return irq;
 
+	isc->irq = irq;
+
 	ret = devm_request_irq(dev, irq, microchip_isc_interrupt, 0,
 			       "microchip-sama7g5-xisc", isc);
 	if (ret < 0) {

-- 
2.34.1