FAILED: patch "[PATCH] media: microchip-isc: synchronize the IRQ before disabling clocks on stop" failed to apply to 5.15-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 19fa5407da5ef3e605cacfcd90f70d8b2c121cd7
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '20261107055805-failed-5.15-19fa5407da5e@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From 19fa5407da5ef3e605cacfcd90f70d8b2c121cd7 Mon Sep 17 00:00:00 2001
From: Balakrishnan Sambath <balakrishnan.s@microchip.com>
Date: Mon, 17 Aug 2026 12:22:00 +0530
Subject: [PATCH] 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: stable@vger.kernel.org
Signed-off-by: Balakrishnan Sambath <balakrishnan.s@microchip.com>
Reviewed-by: Eugen Hristev <ehristev@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
---
 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 ca4f3b5f58aa9..debbc38717de1 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 ad4e98a1dd8fc..f5e322c2e36bc 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 18e1ec0b94fa6..5bd109e93a8fb 100644
--- a/drivers/media/platform/microchip/microchip-sama5d2-isc.c
+++ b/drivers/media/platform/microchip/microchip-sama5d2-isc.c
@@ -448,6 +448,8 @@ 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 07cfe1109ff09..d978ce448a4d2 100644
--- a/drivers/media/platform/microchip/microchip-sama7g5-isc.c
+++ b/drivers/media/platform/microchip/microchip-sama7g5-isc.c
@@ -437,6 +437,8 @@ 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) {
-- 
2.53.0