Re: [RFC PATCH v3 2/5] media: videobuf2: Restructure vb2_buffer

[Hans Verkuil <hverkuil@xs4all.nl>]

Hi Junghak,

Thanks for this patch, it looks much better. I do have a number of comments, though...

On 08/26/2015 01:59 PM, Junghak Sung wrote:
> Remove v4l2-specific stuff from struct vb2_buffer and add member variables
> related with buffer management.
> 
> struct vb2_plane {
>         <snip>
>         /* plane information */
>         unsigned int            bytesused;
>         unsigned int            length;
>         union {
>                 unsigned int    offset;
>                 unsigned long   userptr;
>                 int             fd;
>         } m;
>         unsigned int            data_offset;
> }
> 
> struct vb2_buffer {
>         <snip>
>         /* buffer information */
>         unsigned int            num_planes;
>         unsigned int            index;
>         unsigned int            type;
>         unsigned int            memory;
> 
>         struct vb2_plane        planes[VIDEO_MAX_PLANES];
>         <snip>
> };
> 
> And create struct vb2_v4l2_buffer as container buffer for v4l2 use.
> 
> struct vb2_v4l2_buffer {
>         struct vb2_buffer       vb2_buf;
> 
>         __u32                   flags;
>         __u32                   field;
>         struct timeval          timestamp;
>         struct v4l2_timecode    timecode;
>         __u32                   sequence;
> };
> 
> This patch includes only changes inside of videobuf2. So, it is required to
> modify all device drivers which use videobuf2.
> 
> Signed-off-by: Junghak Sung <jh1009.sung@samsung.com>
> Signed-off-by: Geunyoung Kim <nenggun.kim@samsung.com>
> Acked-by: Seung-Woo Kim <sw0312.kim@samsung.com>
> Acked-by: Inki Dae <inki.dae@samsung.com>
> ---
>  drivers/media/v4l2-core/videobuf2-core.c |  324 +++++++++++++++++-------------
>  include/media/videobuf2-core.h           |   50 ++---
>  include/media/videobuf2-v4l2.h           |   26 +++
>  3 files changed, 236 insertions(+), 164 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index ab00ea0..9266d50 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -35,10 +35,10 @@
>  static int debug;
>  module_param(debug, int, 0644);
>  
> -#define dprintk(level, fmt, arg...)					      \
> -	do {								      \
> -		if (debug >= level)					      \
> -			pr_info("vb2: %s: " fmt, __func__, ## arg); \
> +#define dprintk(level, fmt, arg...)					\
> +	do {								\
> +		if (debug >= level)					\
> +			pr_info("vb2: %s: " fmt, __func__, ## arg);	\

These are just whitespace changes, and that is something it see *a lot* in this
patch. And usually for no clear reason.

Please remove those whitespace changes, it makes a difficult patch even harder
to read than it already is.

>  	} while (0)
>  
>  #ifdef CONFIG_VIDEO_ADV_DEBUG

<snip>

> @@ -656,12 +652,21 @@ static bool __buffers_in_use(struct vb2_queue *q)
>   */
>  static void __fill_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b)
>  {
> +	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
>  	struct vb2_queue *q = vb->vb2_queue;
> +	unsigned int plane;
>  
>  	/* Copy back data such as timestamp, flags, etc. */
> -	memcpy(b, &vb->v4l2_buf, offsetof(struct v4l2_buffer, m));
> -	b->reserved2 = vb->v4l2_buf.reserved2;
> -	b->reserved = vb->v4l2_buf.reserved;

Hmm, I'm not sure why these reserved fields were copied here. I think it was
for compatibility reasons for some old drivers that abused the reserved field.
However, in the new code these reserved fields should probably be explicitly
initialized to 0.

> +	b->index = vb->index;
> +	b->type = vb->type;
> +	b->memory = vb->memory;
> +	b->bytesused = 0;
> +
> +	b->flags = vbuf->flags;
> +	b->field = vbuf->field;
> +	b->timestamp = vbuf->timestamp;
> +	b->timecode = vbuf->timecode;
> +	b->sequence = vbuf->sequence;
>  
>  	if (V4L2_TYPE_IS_MULTIPLANAR(q->type)) {
>  		/*
> @@ -669,21 +674,33 @@ static void __fill_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b)
>  		 * for it. The caller has already verified memory and size.
>  		 */
>  		b->length = vb->num_planes;
> -		memcpy(b->m.planes, vb->v4l2_planes,
> -			b->length * sizeof(struct v4l2_plane));

A similar problem occurs here: the memcpy would have copied the reserved
field in v4l2_plane as well, but that no longer happens, so you need to
do an explicit memset for the reserved field in the new code.

> +		for (plane = 0; plane < vb->num_planes; ++plane) {
> +			struct v4l2_plane *pdst = &b->m.planes[plane];
> +			struct vb2_plane *psrc = &vb->planes[plane];
> +
> +			pdst->bytesused = psrc->bytesused;
> +			pdst->length = psrc->length;
> +			if (q->memory == V4L2_MEMORY_MMAP)
> +				pdst->m.mem_offset = psrc->m.offset;
> +			else if (q->memory == V4L2_MEMORY_USERPTR)
> +				pdst->m.userptr = psrc->m.userptr;
> +			else if (q->memory == V4L2_MEMORY_DMABUF)
> +				pdst->m.fd = psrc->m.fd;
> +			pdst->data_offset = psrc->data_offset;
> +		}
>  	} else {
>  		/*
>  		 * We use length and offset in v4l2_planes array even for
>  		 * single-planar buffers, but userspace does not.
>  		 */
> -		b->length = vb->v4l2_planes[0].length;
> -		b->bytesused = vb->v4l2_planes[0].bytesused;
> +		b->length = vb->planes[0].length;
> +		b->bytesused = vb->planes[0].bytesused;
>  		if (q->memory == V4L2_MEMORY_MMAP)
> -			b->m.offset = vb->v4l2_planes[0].m.mem_offset;
> +			b->m.offset = vb->planes[0].m.offset;
>  		else if (q->memory == V4L2_MEMORY_USERPTR)
> -			b->m.userptr = vb->v4l2_planes[0].m.userptr;
> +			b->m.userptr = vb->planes[0].m.userptr;
>  		else if (q->memory == V4L2_MEMORY_DMABUF)
> -			b->m.fd = vb->v4l2_planes[0].m.fd;
> +			b->m.fd = vb->planes[0].m.fd;
>  	}
>  
>  	/*
> @@ -692,7 +709,7 @@ static void __fill_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b)
>  	b->flags &= ~V4L2_BUFFER_MASK_FLAGS;
>  	b->flags |= q->timestamp_flags & V4L2_BUF_FLAG_TIMESTAMP_MASK;
>  	if ((q->timestamp_flags & V4L2_BUF_FLAG_TIMESTAMP_MASK) !=
> -	    V4L2_BUF_FLAG_TIMESTAMP_COPY) {
> +			V4L2_BUF_FLAG_TIMESTAMP_COPY) {
>  		/*
>  		 * For non-COPY timestamps, drop timestamp source bits
>  		 * and obtain the timestamp source from the queue.
> @@ -767,7 +784,7 @@ EXPORT_SYMBOL(vb2_querybuf);
>  static int __verify_userptr_ops(struct vb2_queue *q)
>  {
>  	if (!(q->io_modes & VB2_USERPTR) || !q->mem_ops->get_userptr ||
> -	    !q->mem_ops->put_userptr)
> +			!q->mem_ops->put_userptr)
>  		return -EINVAL;
>  
>  	return 0;
> @@ -780,7 +797,7 @@ static int __verify_userptr_ops(struct vb2_queue *q)
>  static int __verify_mmap_ops(struct vb2_queue *q)
>  {
>  	if (!(q->io_modes & VB2_MMAP) || !q->mem_ops->alloc ||
> -	    !q->mem_ops->put || !q->mem_ops->mmap)
> +			!q->mem_ops->put || !q->mem_ops->mmap)
>  		return -EINVAL;
>  
>  	return 0;
> @@ -793,8 +810,8 @@ static int __verify_mmap_ops(struct vb2_queue *q)
>  static int __verify_dmabuf_ops(struct vb2_queue *q)
>  {
>  	if (!(q->io_modes & VB2_DMABUF) || !q->mem_ops->attach_dmabuf ||
> -	    !q->mem_ops->detach_dmabuf  || !q->mem_ops->map_dmabuf ||
> -	    !q->mem_ops->unmap_dmabuf)
> +		!q->mem_ops->detach_dmabuf  || !q->mem_ops->map_dmabuf ||
> +		!q->mem_ops->unmap_dmabuf)
>  		return -EINVAL;
>  
>  	return 0;
> @@ -808,7 +825,7 @@ static int __verify_memory_type(struct vb2_queue *q,
>  		enum v4l2_memory memory, enum v4l2_buf_type type)
>  {
>  	if (memory != V4L2_MEMORY_MMAP && memory != V4L2_MEMORY_USERPTR &&
> -	    memory != V4L2_MEMORY_DMABUF) {
> +			memory != V4L2_MEMORY_DMABUF) {
>  		dprintk(1, "unsupported memory type\n");
>  		return -EINVAL;
>  	}
> @@ -927,7 +944,7 @@ static int __reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
>  	 * Driver also sets the size and allocator context for each plane.
>  	 */
>  	ret = call_qop(q, queue_setup, q, NULL, &num_buffers, &num_planes,
> -		       q->plane_sizes, q->alloc_ctx);
> +			q->plane_sizes, q->alloc_ctx);
>  	if (ret)
>  		return ret;
>  
> @@ -952,7 +969,7 @@ static int __reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
>  		num_buffers = allocated_buffers;
>  
>  		ret = call_qop(q, queue_setup, q, NULL, &num_buffers,
> -			       &num_planes, q->plane_sizes, q->alloc_ctx);
> +				&num_planes, q->plane_sizes, q->alloc_ctx);
>  
>  		if (!ret && allocated_buffers < num_buffers)
>  			ret = -ENOMEM;
> @@ -1040,7 +1057,7 @@ static int __create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create
>  	 * buffer and their sizes are acceptable
>  	 */
>  	ret = call_qop(q, queue_setup, q, &create->format, &num_buffers,
> -		       &num_planes, q->plane_sizes, q->alloc_ctx);
> +			&num_planes, q->plane_sizes, q->alloc_ctx);
>  	if (ret)
>  		return ret;
>  
> @@ -1063,7 +1080,7 @@ static int __create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create
>  		 * queue driver has set up
>  		 */
>  		ret = call_qop(q, queue_setup, q, &create->format, &num_buffers,
> -			       &num_planes, q->plane_sizes, q->alloc_ctx);
> +				&num_planes, q->plane_sizes, q->alloc_ctx);
>  
>  		if (!ret && allocated_buffers < num_buffers)
>  			ret = -ENOMEM;
> @@ -1183,8 +1200,8 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
>  		return;
>  
>  	if (WARN_ON(state != VB2_BUF_STATE_DONE &&
> -		    state != VB2_BUF_STATE_ERROR &&
> -		    state != VB2_BUF_STATE_QUEUED))
> +		state != VB2_BUF_STATE_ERROR &&
> +		state != VB2_BUF_STATE_QUEUED))
>  		state = VB2_BUF_STATE_ERROR;
>  
>  #ifdef CONFIG_VIDEO_ADV_DEBUG

All the chunks above are all spurious whitespace changes. As mentioned in the beginning,
please remove all those pointless whitespace changes!

There are a lot more of these, but I won't comment on them anymore.

Basically this patch looks good to me, so once I have the next version without all the
whitespace confusion and with the reserved field issues solved I'll do a final review.

BTW, did you test this with 'v4l2-compliance -s' and with the vivid driver? Just to
make sure you didn't break anything.

Regards,

	Hans