Hi Jacopo,
Thank you for the patch.
On Mon, Oct 07, 2024 at 02:42:24PM +0200, Jacopo Mondi wrote:
> There apparently is no reason to require 3 queued buffers to call
> streamon() for the RkISP1 as the driver operates with a scratch buffer
> where frames can be directed to if there's no available buffer provided
> by userspace.
>
> Reduce the number of required buffers to 1 to allow applications to
> operate with a single queued buffer.
>
> Tested with libcamera, by operating with a single capture a request. The
s/capture a/capture/
> same request (and associated capture buffer) gets recycled once
> completed. This of course causes a frame rate drop but doesn't hinder
> operations.
>
> Signed-off-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx>
> ---
>
> Adam,
> a few months ago you were exercizing your pinhole app with a single capture
> request for StillCapture operations and you got the video device to hang because
> no enough buffers where provided.
>
> This small change should be enough to unblock you. Could you maybe give it a
> spin if you're still working on this ?
>
> Thanks
> j
> ---
>
> drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
> index 2bddb4fa8a5c..34adaecdee54 100644
> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-capture.c
> @@ -35,8 +35,6 @@
> #define RKISP1_SP_DEV_NAME RKISP1_DRIVER_NAME "_selfpath"
> #define RKISP1_MP_DEV_NAME RKISP1_DRIVER_NAME "_mainpath"
>
> -#define RKISP1_MIN_BUFFERS_NEEDED 3
> -
> enum rkisp1_plane {
> RKISP1_PLANE_Y = 0,
> RKISP1_PLANE_CB = 1,
> @@ -1563,7 +1561,7 @@ static int rkisp1_register_capture(struct rkisp1_capture *cap)
> q->ops = &rkisp1_vb2_ops;
> q->mem_ops = &vb2_dma_contig_memops;
> q->buf_struct_size = sizeof(struct rkisp1_buffer);
> - q->min_queued_buffers = RKISP1_MIN_BUFFERS_NEEDED;
> + q->min_queued_buffers = 1;
min_queued_buffers controls two things in vb2:
- It controls the minimum number of buffers that can be allocated, by
setting
if (q->min_reqbufs_allocation < q->min_queued_buffers + 1)
q->min_reqbufs_allocation = q->min_queued_buffers + 1;
in vb2_core_queue_init(). Note that this ony impacts the
VIDIOC_REQBUFS ioctl, VIDIOC_CREATE_BUFS can still allocate a lower
number of buffers.
- It delays the .start_streaming() call until min_queued_buffers buffers
have been queued.
This patch brings a clear improvement as it allows operating with a
single buffer. Ideally though, it would be nice to set
min_queued_buffers to 0, so that .start_streaming() gets called
synchronously with VIDIOC_STREAMON. Otherwise stream start errors can be
reported later, at VIDIOC_QBUF time.
I expect going for 0 will require more changes in the driver, so I'm
fine merging this patch as-is as a first step.
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> q->lock = &node->vlock;
> q->dev = cap->rkisp1->dev;
--
Regards,
Laurent Pinchart
