On Sat Mar 28 17:34:51 2026 +0100, Jacopo Mondi wrote:
> The rzv2h-ivc driver fails to handle back-2-back streaming sessions that
> do not go through a peripheral reset. As the driver uses an autosuspend
> delay of 2 seconds, it is quite possible that two consecutive streaming
> sessions won't go through a suspend/resume sequence.
>
> If the peripheral is not reset the second streaming session hangs and no
> frames are delivered to the ISP.
>
> This is because the stop_streaming() procedure implemented in the driver
> doesn't match what's prescribed by the chip datasheet:
>
> 1) The chip manual suggests to poll the RZV2H_IVC_FM_INT_STAT_STPEND bit
> of RZV2H_IVC_REG_FM_INT_STA instead of polling on RZV2H_IVC_REG_FM_STOP
> and prescribes to clear the bit after polling has completed
>
> 2) More importantly: the RZV2H_IVC_REG_FM_STOP_FSTOP bit has to be set
> on RZV2H_IVC_REG_FM_STOP -only- if a frame transfer to the ISP is in
> progress. Setting the RZV2H_IVC_REG_FM_STOP_FSTOP bit when no frame is
> being transferred causes the polling routine to timeout and the next
> streaming session fails to start
>
> As a frame transfer of an image in 1920x1080@10bi takes 5 milliseconds
> at most, it is quite possible that the frame transfer completion interrupt
> races with the stop procedure.
>
> Instead of forcing a frame transfer abort, simply wait for the
> in-progress transfer to complete by polling the ivc->vvalid_ifp status
> variable in an hand-rolled loop that allows to inspect the variable
> while holding the spinlock, to allow the irq handler to complete the
> current buffer.
>
> With this change, streaming back-2-back without suspending the
> peripheral works successfully.
>
> Cc: [email protected]
> Fixes: f0b3984d821b ("media: platform: Add Renesas Input Video Control block
> driver")
> Signed-off-by: Jacopo Mondi <[email protected]>
> Reviewed-by: Daniel Scally <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
.../platform/renesas/rzv2h-ivc/rzv2h-ivc-video.c | 31 ++++++++++++++++++----
1 file changed, 26 insertions(+), 5 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 b167f1bab7ef..932fed38cf3f 100644
--- a/drivers/media/platform/renesas/rzv2h-ivc/rzv2h-ivc-video.c
+++ b/drivers/media/platform/renesas/rzv2h-ivc/rzv2h-ivc-video.c
@@ -297,12 +297,33 @@ err_return_buffers:
static void rzv2h_ivc_stop_streaming(struct vb2_queue *q)
{
struct rzv2h_ivc *ivc = vb2_get_drv_priv(q);
- u32 val = 0;
+ unsigned int loop = 5;
- rzv2h_ivc_write(ivc, RZV2H_IVC_REG_FM_STOP,
RZV2H_IVC_REG_FM_STOP_FSTOP);
- readl_poll_timeout(ivc->base + RZV2H_IVC_REG_FM_STOP,
- val, !(val & RZV2H_IVC_REG_FM_STOP_FSTOP),
- 10 * USEC_PER_MSEC, 250 * USEC_PER_MSEC);
+ /*
+ * If no frame transfer is in progress, we're done, otherwise, wait for
+ * the transfer to complete.
+ *
+ * Transferring a 1920x1080@10bit frame to the ISP takes less than 5
+ * msec so sleep for 2.5 msec (+- 25%) and give up after 5 attempts.
+ */
+ for (; loop > 0; loop--) {
+ unsigned int vvalid_ifp;
+
+ /*
+ * Inspect the ivc->vvalid_ifp variable holding the spinlock not
+ * to the race with the rzv2h_ivc_buffer_done() call in the irq
+ * handler.
+ */
+ scoped_guard(spinlock_irq, &ivc->spinlock) {
+ vvalid_ifp = ivc->vvalid_ifp;
+ }
+ if (vvalid_ifp < 2)
+ break;
+
+ fsleep(2500);
+ }
+ if (!loop)
+ dev_err(ivc->dev, "Failed to stop streaming\n");
rzv2h_ivc_return_buffers(ivc, VB2_BUF_STATE_ERROR);
video_device_pipeline_stop(&ivc->vdev.dev);
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