On Thu, 5 Mar 2009, Robert Jarzmik wrote:
> The last buffer queued will often overrun, as the DMA chain
> is finished, and the time the dma irq handler is activated,
> the QIF fifos are filled by the sensor.
>
> The fix is to ignore the overrun condition on the last
> queued buffer, and restart the capture only on intermediate
> buffers of the chain.
>
> Signed-off-by: Robert Jarzmik <robert.jarzmik@xxxxxxx>
> ---
> drivers/media/video/pxa_camera.c | 8 ++++++--
> 1 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/video/pxa_camera.c b/drivers/media/video/pxa_camera.c
> index 16bf0a3..dd56c35 100644
> --- a/drivers/media/video/pxa_camera.c
> +++ b/drivers/media/video/pxa_camera.c
> @@ -734,14 +734,18 @@ static void pxa_camera_dma_irq(int channel, struct pxa_camera_dev *pcdev,
> status & DCSR_ENDINTR ? "EOF " : "", vb, DDADR(channel));
>
> if (status & DCSR_ENDINTR) {
> - if (camera_status & overrun) {
> + /*
> + * It's normal if the last frame creates an overrun, as there
> + * are no more DMA descriptors to fetch from QIF fifos
> + */
> + if (camera_status & overrun
> + && !list_is_last(pcdev->capture.next, &pcdev->capture)) {
On a second look - didn't you want to test for ->active being the last?
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
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