[PATCH v2 04/10] media: microchip-isc: disable histogram and flush AWB work on teardown

[Balakrishnan Sambath]

isc_stop_streaming() and the isc_start_streaming() error path dropped the
runtime PM reference with the histogram still enabled. A HISDONE firing
just before the stop, or a failed isc_update_profile() on the start path,
can queue isc_awb_work(), which reads the histogram registers before
taking its own PM reference and faults on the unclocked device.

Disable the histogram, synchronize the IRQ and flush the work before
dropping the PM reference on both paths. synchronize_irq() must come
before cancel_work_sync(), so an in-flight handler cannot re-queue
awb_work after it is cancelled.

Fixes: 91b4e487b0c6 ("media: microchip: add ISC driver as Microchip ISC")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Balakrishnan Sambath <balakrishnan.s@xxxxxxxxxxxxx>
---
 drivers/media/platform/microchip/microchip-isc-base.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/media/platform/microchip/microchip-isc-base.c b/drivers/media/platform/microchip/microchip-isc-base.c
index 3245dd7cb980..f7fbd3cd8edc 100644
--- a/drivers/media/platform/microchip/microchip-isc-base.c
+++ b/drivers/media/platform/microchip/microchip-isc-base.c
@@ -382,6 +382,13 @@ static int isc_start_streaming(struct vb2_queue *vq, unsigned int count)
 	return 0;
 
 err_configure:
+	isc_set_histogram(isc, false);
+
+	/* let a running IRQ handler finish before the clock is disabled */
+	synchronize_irq(isc->irq);
+
+	cancel_work_sync(&isc->awb_work);
+
 	pm_runtime_put_sync(isc->dev);
 err_pm_get:
 	v4l2_subdev_call(isc->current_subdev->sd, video, s_stream, 0);
@@ -425,9 +432,13 @@ static void isc_stop_streaming(struct vb2_queue *vq)
 	/* Disable DMA interrupt */
 	regmap_write(isc->regmap, ISC_INTDIS, ISC_INT_DDONE);
 
+	isc_set_histogram(isc, false);
+
 	/* let a running IRQ handler finish before the clock is disabled */
 	synchronize_irq(isc->irq);
 
+	cancel_work_sync(&isc->awb_work);
+
 	pm_runtime_put_sync(isc->dev);
 
 	/* Disable stream on the sub device */

-- 
2.34.1