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media: rzv2h-ivc: Wait for frame end in stop_streaming

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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: stable@vger.kernel.org
Fixes: f0b3984d82 ("media: platform: Add Renesas Input Video Control block driver")
Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@ideasonboard.com>
Reviewed-by: Daniel Scally <dan.scally@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
This commit is contained in:
Jacopo Mondi 2026-03-28 17:34:51 +01:00 committed by Hans Verkuil
parent 8cb2d88fa5
commit b4e6ddce16
1 changed files with 26 additions and 5 deletions
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31
drivers/media/platform/renesas/rzv2h-ivc/rzv2h-ivc-video.c
View File

@ -297,12 +297,33 @@ static int rzv2h_ivc_start_streaming(struct vb2_queue *q, unsigned int count)
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);