Hi Guennadi,
On Wed, Aug 24, 2011 at 11:41, Guennadi Liakhovetski
<[email protected]> wrote:
> The two recently added ioctl()s VIDIOC_CREATE_BUFS and VIDIOC_PREPARE_BUF
> allow user-space applications to allocate video buffers of different
> sizes and hand them over to the driver for fast switching between
> different frame formats. This patch adds support for buffers of different
> sizes on the same buffer-queue to vb2.
>
> Signed-off-by: Guennadi Liakhovetski <[email protected]>
> Cc: Hans Verkuil <[email protected]>
> Cc: Laurent Pinchart <[email protected]>
> Cc: Marek Szyprowski <[email protected]>
> Cc: Mauro Carvalho Chehab <[email protected]>
> Cc: Pawel Osciak <[email protected]>
> Cc: Sakari Ailus <[email protected]>
> ---
> drivers/media/video/videobuf2-core.c | 278
> ++++++++++++++++++++++++++++------
> include/media/videobuf2-core.h | 31 +++--
> 2 files changed, 252 insertions(+), 57 deletions(-)
>
> diff --git a/drivers/media/video/videobuf2-core.c
> b/drivers/media/video/videobuf2-core.c
> index 8a81a89..fed6f2d 100644
> --- a/drivers/media/video/videobuf2-core.c
> +++ b/drivers/media/video/videobuf2-core.c
<snip>
> @@ -454,7 +465,7 @@ static bool __buffers_in_use(struct vb2_queue *q)
> */
> int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
> {
> - unsigned int num_buffers, num_planes;
> + unsigned int num_buffers, allocated_buffers, num_planes = 0;
> unsigned long plane_sizes[VIDEO_MAX_PLANES];
> int ret = 0;
>
> @@ -503,7 +514,7 @@ int vb2_reqbufs(struct vb2_queue *q, struct
> v4l2_requestbuffers *req)
> return -EBUSY;
> }
>
> - __vb2_queue_free(q);
> + __vb2_queue_free(q, q->num_buffers);
>
> /*
> * In case of REQBUFS(0) return immediately without calling
> @@ -538,44 +549,166 @@ int vb2_reqbufs(struct vb2_queue *q, struct
> v4l2_requestbuffers *req)
> return -ENOMEM;
> }
>
> + allocated_buffers = ret;
> +
> /*
> * Check if driver can handle the allocated number of buffers.
> */
> - if (ret < num_buffers) {
> - unsigned int orig_num_buffers;
> + if (allocated_buffers < num_buffers) {
> + num_buffers = allocated_buffers;
>
> - orig_num_buffers = num_buffers = ret;
> ret = call_qop(q, queue_setup, q, NULL, &num_buffers,
> &num_planes, plane_sizes, q->alloc_ctx);
> - if (ret)
> - goto free_mem;
>
> - if (orig_num_buffers < num_buffers) {
> + if (!ret && allocated_buffers < num_buffers)
> ret = -ENOMEM;
> - goto free_mem;
> - }
>
> /*
> - * Ok, driver accepted smaller number of buffers.
> + * Either the driver has accepted a smaller number of buffers,
> + * or .queue_setup() returned an error
> */
> - ret = num_buffers;
> + }
> +
> + q->num_buffers = allocated_buffers;
> +
> + if (ret < 0) {
> + __vb2_queue_free(q, allocated_buffers);
> + return ret;
> }
>
> /*
> * Return the number of successfully allocated buffers
> * to the userspace.
> */
> - req->count = ret;
> + req->count = allocated_buffers;
>
> return 0;
> -
> -free_mem:
> - __vb2_queue_free(q);
> - return ret;
> }
> EXPORT_SYMBOL_GPL(vb2_reqbufs);
>
> /**
> + * vb2_create_bufs() - Allocate buffers and any required auxiliary structs
> + * @q: videobuf2 queue
> + * @create: creation parameters, passed from userspace to
> vidioc_create_bufs
> + * handler in driver
> + *
> + * Should be called from vidioc_create_bufs ioctl handler of a driver.
> + * This function:
> + * 1) verifies parameter sanity
> + * 2) calls the .queue_setup() queue operation
> + * 3) performs any necessary memory allocations
> + *
> + * The return values from this function are intended to be directly returned
> + * from vidioc_create_bufs handler in driver.
> + */
> +int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
> +{
> + unsigned int num_planes, num_buffers = create->count,
> allocated_buffers;
> + unsigned long plane_sizes[VIDEO_MAX_PLANES];
> + int ret = 0;
> +
> + if (q->fileio) {
> + dprintk(1, "%s(): file io in progress\n", __func__);
> + return -EBUSY;
> + }
> +
> + if (create->memory != V4L2_MEMORY_MMAP
> + && create->memory != V4L2_MEMORY_USERPTR) {
> + dprintk(1, "%s(): unsupported memory type\n", __func__);
> + return -EINVAL;
> + }
> +
> + if (create->format.type != q->type) {
> + dprintk(1, "%s(): requested type is incorrect\n", __func__);
> + return -EINVAL;
> + }
> +
> + /*
> + * Make sure all the required memory ops for given memory type
> + * are available.
> + */
> + if (create->memory == V4L2_MEMORY_MMAP && __verify_mmap_ops(q)) {
> + dprintk(1, "%s(): MMAP for current setup unsupported\n",
> __func__);
> + return -EINVAL;
> + }
> +
> + if (create->memory == V4L2_MEMORY_USERPTR && __verify_userptr_ops(q))
> {
> + dprintk(1, "%s(): USERPTR for current setup unsupported\n",
> __func__);
> + return -EINVAL;
> + }
> +
> + if (q->num_buffers == VIDEO_MAX_FRAME) {
> + dprintk(1, "%s(): maximum number of buffers already
> allocated\n",
> + __func__);
> + return -ENOBUFS;
> + }
I think we should be verifying that q->num_buffers + create->count <=
VIDEO_MAX_FRAME.
> +
> + create->index = q->num_buffers;
> +
> + if (!q->num_buffers) {
> + memset(q->alloc_ctx, 0, sizeof(q->alloc_ctx));
> + q->memory = create->memory;
> + }
> +
> + /*
> + * Ask the driver, whether the requested number of buffers, planes per
> + * buffer and their sizes are acceptable
> + */
> + ret = call_qop(q, queue_setup, q, &create->format, &num_buffers,
> + &num_planes, plane_sizes, q->alloc_ctx);
I don't see you zeroing neither num_planes nor plane_sizes[] in
vb2_create_bufs and vb2_reqbufs. Since instead of always requiring the
driver to fill them, you've introduced the "non-zero num_planes and/or
plane_sizes" case (see my comment for queue_setup() documentation in
videobuf2-core.h), it looks to me that the drivers will be getting
random values in num_planes and plane_sizes in queue_setup() and will
have to attempt to use them. Ditto for all other qop calls to
queue_setup in this file (in vb2_reqbufs as well).
> + if (ret)
> + return ret;
> +
> + /* Finally, allocate buffers and video memory */
> + ret = __vb2_queue_alloc(q, create->memory, num_buffers,
> + num_planes, plane_sizes);
> + if (ret < 0) {
> + dprintk(1, "Memory allocation failed with error: %d\n", ret);
> + return ret;
> + }
> +
> + allocated_buffers = ret;
> +
> + /*
> + * Check if driver can handle the so far allocated number of buffers.
> + */
> + if (ret < num_buffers) {
> + num_buffers = ret;
> +
> + /*
> + * q->num_buffers contains the total number of buffers, that
> the
> + * queue driver has set up
> + */
> + ret = call_qop(q, queue_setup, q, &create->format,
> &num_buffers,
> + &num_planes, plane_sizes, q->alloc_ctx);
We need to be sure that drivers understand that num_buffers is _in
addition_ to previous allocations if fmt!=NULL (see my comments for
videobuf2-core.h below).
> +
> + if (!ret && allocated_buffers < num_buffers)
> + ret = -ENOMEM;
> +
> + /*
> + * Either the driver has accepted a smaller number of buffers,
> + * or .queue_setup() returned an error
> + */
> + }
> +
> + q->num_buffers += allocated_buffers;
> +
> + if (ret < 0) {
> + __vb2_queue_free(q, allocated_buffers);
> + return ret;
> + }
> +
> + /*
> + * Return the number of successfully allocated buffers
> + * to the userspace.
> + */
> + create->count = allocated_buffers;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(vb2_create_bufs);
> +
<snip>
> /**
> + * vb2_prepare_buf() - Pass ownership of a buffer from userspace to the
> kernel
> + * @q: videobuf2 queue
> + * @b: buffer structure passed from userspace to vidioc_prepare_buf
> + * handler in driver
> + *
> + * Should be called from vidioc_prepare_buf ioctl handler of a driver.
> + * This function:
> + * 1) verifies the passed buffer,
> + * 2) calls buf_prepare callback in the driver (if provided), in which
> + * driver-specific buffer initialization can be performed,
> + *
> + * The return values from this function are intended to be directly returned
> + * from vidioc_prepare_buf handler in driver.
> + */
> +int vb2_prepare_buf(struct vb2_queue *q, const struct v4l2_buffer *b)
> +{
> + struct vb2_buffer *vb;
> +
> + if (q->fileio) {
> + dprintk(1, "%s(): file io in progress\n", __func__);
> + return -EBUSY;
> + }
> +
> + if (b->type != q->type) {
> + dprintk(1, "%s(): invalid buffer type\n", __func__);
> + return -EINVAL;
> + }
> +
> + if (b->index >= q->num_buffers) {
> + dprintk(1, "%s(): buffer index out of range\n", __func__);
> + return -EINVAL;
> + }
> +
> + vb = q->bufs[b->index];
> + if (NULL == vb) {
> + /* Should never happen */
> + dprintk(1, "%s(): buffer is NULL\n", __func__);
> + return -EINVAL;
> + }
> +
> + if (b->memory != q->memory) {
> + dprintk(1, "%s(): invalid memory type\n", __func__);
> + return -EINVAL;
> + }
> +
> + if (vb->state != VB2_BUF_STATE_DEQUEUED) {
> + dprintk(1, "%s(): invalid buffer state %d\n", __func__,
> vb->state);
> + return -EINVAL;
> + }
> +
> + return __buf_prepare(vb, b);
> +}
> +EXPORT_SYMBOL_GPL(vb2_prepare_buf);
> +
I don't see vb->state being set to VB2_BUF_STATE_PREPARED anywhere...
Shouldn't it be done here? Otherwise we'll be calling buf_prepare
again on qbuf...
<snip>
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index d043132..ddebcd3 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -172,13 +172,17 @@ struct vb2_buffer {
> /**
> * struct vb2_ops - driver-specific callbacks
> *
> - * @queue_setup: called from a VIDIOC_REQBUFS handler, before
> - * memory allocation; driver should return the required
> - * number of buffers in num_buffers, the required number
> - * of planes per buffer in num_planes; the size of each
> - * plane should be set in the sizes[] array and optional
> - * per-plane allocator specific context in alloc_ctxs[]
> - * array
> + * @queue_setup: called from VIDIOC_REQBUFS and VIDIOC_CREATE_BUFS
> + * handlers, before memory allocation. When called with
> + * zeroed num_planes or plane sizes, the driver should
> + * return the required number of buffers in num_buffers,
> + * the required number of planes per buffer in
> num_planes;
> + * the size of each plane should be set in the sizes[]
> + * array and optional per-plane allocator specific
> context
> + * in alloc_ctxs[] array. If num_planes and sizes[] are
> + * both non-zero, the driver should use them. Otherwise
> the
> + * driver must make no assumptions about the buffers,
> that
> + * will be made available to it.
Could you explain why different behavior from a driver is required
depending on the values of num_planes and plane_sizes? Are you
expecting vb2 to fill num_planes and plane_sizes? That would require
it to parse the format...
Another subtle problem here is that on vb2_reqbufs, we call
queue_setup() asking the driver whether it can manage the allocated
number of buffers. Now with queue_setup being called from
vb2_create_bufs as well, we need to make sure that the driver
understands that num_buffers passed then is only for buffers of the
format passed to create. In other words, if fmt==NULL, driver must be
able to handle num_buffers buffers of current format; else if fmt !=
NULL, the driver must be able to handle any previously allocated
buffers _plus_ the number passed to this queue_setup call. This not
only means last call to queue_setup with fmt==NULL plus current call,
but previous call with fmt==NULL _plus_ all previous calls with
fmt!=NULL _plus_ the current call.
<snip>
Could you share the userspace code that you used for testing this? I
just wanted to get a feel of how those new ioctls fall into place
together. Also, did you try multiple CREATE_BUFS calls?
--
Best regards,
Pawel Osciak
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