On Wed Feb 11 15:30:00 2026 +0100, Jacopo Mondi wrote:
> The scheduling of a new buffer transfer in the IVC driver is triggered
> by two occurrences of the "frame completed" interrupt.
>
> The first interrupt occurrence identifies when all image data have been
> transferred to the ISP, the second occurrence identifies when the
> post-transfer VBLANK has completed and a new buffer can be transferred.
>
> Under heavy system load conditions the actual execution of the workqueue
> item might be delayed and two items might happen to run concurrently,
> leading to a new frame transfer being triggered while the previous one
> has not yet finished.
>
> This error condition is only visible because the driver maintains a
> status variable that counts the number of interrupts since the last
> transfer, and warns in case an IRQ happens before the counter has been
> reset.
>
> To ensure sequential execution of the worqueue items and avoid a double
> buffer transfer to run concurrently, protect the whole function body
> with the spinlock that so far was solely used to reset the counter and
> inspect the interrupt counter variable at the beginning of the buffer
> transfer function.
>
> As soon as the ongoing transfer completes, the workqueue item will be
> re-scheduled and will consume the pending buffer.
>
> Cc: [email protected]
> Fixes: f0b3984d821b ("media: platform: Add Renesas Input Video Control block
> driver")
> Reviewed-by: Daniel Scally <[email protected]>
> Signed-off-by: Jacopo Mondi <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/platform/renesas/rzv2h-ivc/rzv2h-ivc-video.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
---
diff --git a/drivers/media/platform/renesas/rzv2h-ivc/rzv2h-ivc-video.c
b/drivers/media/platform/renesas/rzv2h-ivc/rzv2h-ivc-video.c
index a22aee0fe1cf..3580a57738a6 100644
--- a/drivers/media/platform/renesas/rzv2h-ivc/rzv2h-ivc-video.c
+++ b/drivers/media/platform/renesas/rzv2h-ivc/rzv2h-ivc-video.c
@@ -149,6 +149,11 @@ static void rzv2h_ivc_transfer_buffer(struct work_struct
*work)
buffers.work);
struct rzv2h_ivc_buf *buf;
+ guard(spinlock_irqsave)(&ivc->spinlock);
+
+ if (ivc->vvalid_ifp)
+ return;
+
/* Setup buffers */
scoped_guard(spinlock_irqsave, &ivc->buffers.lock) {
buf = list_first_entry_or_null(&ivc->buffers.queue,
@@ -163,9 +168,7 @@ static void rzv2h_ivc_transfer_buffer(struct work_struct
*work)
buf->addr = vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0);
rzv2h_ivc_write(ivc, RZV2H_IVC_REG_AXIRX_SADDL_P0, buf->addr);
- scoped_guard(spinlock_irqsave, &ivc->spinlock) {
- ivc->vvalid_ifp = 2;
- }
+ ivc->vvalid_ifp = 2;
rzv2h_ivc_write(ivc, RZV2H_IVC_REG_FM_FRCON, 0x1);
}
@@ -200,7 +203,7 @@ static void rzv2h_ivc_buf_queue(struct vb2_buffer *vb)
}
scoped_guard(spinlock_irq, &ivc->spinlock) {
- if (vb2_is_streaming(vb->vb2_queue) && !ivc->vvalid_ifp)
+ if (vb2_is_streaming(vb->vb2_queue))
queue_work(ivc->buffers.async_wq, &ivc->buffers.work);
}
}
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