Message-ID: <20230313180108.GA22646@pendragon.ideasonboard.com>
Date:   Mon, 13 Mar 2023 20:01:08 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Benjamin Gaignard <benjamin.gaignard@...labora.com>
Cc:     tfiga@...omium.org, m.szyprowski@...sung.com, mchehab@...nel.org,
        ming.qian@....com, shijie.qin@....com, eagle.zhou@....com,
        bin.liu@...iatek.com, matthias.bgg@...il.com,
        angelogioacchino.delregno@...labora.com, tiffany.lin@...iatek.com,
        andrew-ct.chen@...iatek.com, yunfei.dong@...iatek.com,
        stanimir.k.varbanov@...il.com, quic_vgarodia@...cinc.com,
        agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        ezequiel@...guardiasur.com.ar, p.zabel@...gutronix.de,
        daniel.almeida@...labora.com, hverkuil-cisco@...all.nl,
        jerbel@...nel.org, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, kernel@...labora.com
Subject: Re: [RFC 1/4] media: videobuf2: Use vb2_get_buffer() as helper
 everywhere

Hi Benjamin,

Thank you for the patch.

On Mon, Mar 13, 2023 at 02:59:13PM +0100, Benjamin Gaignard wrote:
> The first step before changing how vb2 buffers are stored into queue
> is to avoid direct call to bufs arrays.

s/call/access/

> This patch add 2 helpers functions to set and delete vb2 buffers

s/add/adds/

> from a queue. With these 2 and vb2_get_buffer(), bufs field of
> struct vb2_queue becomes like a private member of the structure.

As the patch does more than using vb2_get_buffer() everywhere, I would
rewrite the subject line to

media: videobuf2: Access vb2_queue bufs array through helper functions

> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...labora.com>
> ---
>  .../media/common/videobuf2/videobuf2-core.c   | 69 ++++++++++---------
>  .../media/common/videobuf2/videobuf2-v4l2.c   | 17 +++--
>  drivers/media/platform/amphion/vpu_dbg.c      |  4 +-
>  .../platform/mediatek/jpeg/mtk_jpeg_core.c    |  2 +-
>  .../vcodec/vdec/vdec_vp9_req_lat_if.c         |  2 +-
>  drivers/media/test-drivers/visl/visl-dec.c    | 16 +++--
>  include/media/videobuf2-core.h                | 20 ++++++
>  7 files changed, 81 insertions(+), 49 deletions(-)
> 
> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> index cf6727d9c81f..b51152ace763 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -359,7 +359,7 @@ static void __setup_offsets(struct vb2_buffer *vb)
>  	unsigned long off = 0;
>  
>  	if (vb->index) {
> -		struct vb2_buffer *prev = q->bufs[vb->index - 1];
> +		struct vb2_buffer *prev = vb2_get_buffer(q, vb->index - 1);
>  		struct vb2_plane *p = &prev->planes[prev->num_planes - 1];
>  
>  		off = PAGE_ALIGN(p->m.offset + p->length);
> @@ -437,7 +437,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
>  		}
>  		call_void_bufop(q, init_buffer, vb);
>  
> -		q->bufs[vb->index] = vb;
> +		vb2_set_buffer(q, vb);
>  
>  		/* Allocate video buffer memory for the MMAP type */
>  		if (memory == VB2_MEMORY_MMAP) {
> @@ -445,7 +445,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
>  			if (ret) {
>  				dprintk(q, 1, "failed allocating memory for buffer %d\n",
>  					buffer);
> -				q->bufs[vb->index] = NULL;
> +				vb2_del_buffer(q, vb);
>  				kfree(vb);

vb2_del_buffer() make it sounds like the buffer gets deleted, yet you
free it right after. That could be confusing. One option would be to
call the function vb2_remove_buffer() (or possibly even better as it's
more explicit, vb2_queue_remove_buffer()). Another one would be to move
the kfree() call to vb2_del_buffer().

Similarly, vb2_add_buffer() or vb2_queue_add_buffer() would be better
names for vb2_set_buffer().

>  				break;
>  			}
> @@ -460,7 +460,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
>  				dprintk(q, 1, "buffer %d %p initialization failed\n",
>  					buffer, vb);
>  				__vb2_buf_mem_free(vb);
> -				q->bufs[vb->index] = NULL;
> +				vb2_del_buffer(q, vb);
>  				kfree(vb);
>  				break;
>  			}
> @@ -483,7 +483,7 @@ static void __vb2_free_mem(struct vb2_queue *q, unsigned int buffers)
>  
>  	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
>  	     ++buffer) {
> -		vb = q->bufs[buffer];
> +		vb = vb2_get_buffer(q, buffer);

I wonder if this could be optimized in subsequent patches by using a
list walk instead of a for loop on the buffer index. Same in multiple
locations below. I'd add the list walks right after this patch. A
vb2_buffer list walk macro (for_each_vb2_buffer for instance) would be
useful.

>  		if (!vb)
>  			continue;
>  
> @@ -511,7 +511,7 @@ static void __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
>  	/* Call driver-provided cleanup function for each buffer, if provided */
>  	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
>  	     ++buffer) {
> -		struct vb2_buffer *vb = q->bufs[buffer];
> +		struct vb2_buffer *vb = vb2_get_buffer(q, buffer);
>  
>  		if (vb && vb->planes[0].mem_priv)
>  			call_void_vb_qop(vb, buf_cleanup, vb);
> @@ -591,8 +591,10 @@ static void __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
>  	/* Free vb2 buffers */
>  	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
>  	     ++buffer) {
> -		kfree(q->bufs[buffer]);
> -		q->bufs[buffer] = NULL;
> +		struct vb2_buffer *vb2 = vb2_get_buffer(q, buffer);
> +
> +		vb2_del_buffer(q, vb2);
> +		kfree(vb2);
>  	}
>  
>  	q->num_buffers -= buffers;
> @@ -628,7 +630,7 @@ static bool __buffers_in_use(struct vb2_queue *q)
>  {
>  	unsigned int buffer;
>  	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
> -		if (vb2_buffer_in_use(q, q->bufs[buffer]))
> +		if (vb2_buffer_in_use(q, vb2_get_buffer(q, buffer)))
>  			return true;
>  	}
>  	return false;
> @@ -636,7 +638,7 @@ static bool __buffers_in_use(struct vb2_queue *q)
>  
>  void vb2_core_querybuf(struct vb2_queue *q, unsigned int index, void *pb)
>  {
> -	call_void_bufop(q, fill_user_buffer, q->bufs[index], pb);
> +	call_void_bufop(q, fill_user_buffer, vb2_get_buffer(q, index), pb);
>  }
>  EXPORT_SYMBOL_GPL(vb2_core_querybuf);
>  
> @@ -1547,7 +1549,7 @@ int vb2_core_prepare_buf(struct vb2_queue *q, unsigned int index, void *pb)
>  	struct vb2_buffer *vb;
>  	int ret;
>  
> -	vb = q->bufs[index];
> +	vb = vb2_get_buffer(q, index);
>  	if (vb->state != VB2_BUF_STATE_DEQUEUED) {
>  		dprintk(q, 1, "invalid buffer state %s\n",
>  			vb2_state_name(vb->state));
> @@ -1618,7 +1620,7 @@ static int vb2_start_streaming(struct vb2_queue *q)
>  		 * correctly return them to vb2.
>  		 */
>  		for (i = 0; i < q->num_buffers; ++i) {
> -			vb = q->bufs[i];
> +			vb = vb2_get_buffer(q, i);
>  			if (vb->state == VB2_BUF_STATE_ACTIVE)
>  				vb2_buffer_done(vb, VB2_BUF_STATE_QUEUED);
>  		}
> @@ -1646,7 +1648,7 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb,
>  		return -EIO;
>  	}
>  
> -	vb = q->bufs[index];
> +	vb = vb2_get_buffer(q, index);
>  
>  	if (!req && vb->state != VB2_BUF_STATE_IN_REQUEST &&
>  	    q->requires_requests) {
> @@ -2022,12 +2024,15 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
>  	 * to vb2 in stop_streaming().
>  	 */
>  	if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
> -		for (i = 0; i < q->num_buffers; ++i)
> -			if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE) {
> +		for (i = 0; i < q->num_buffers; ++i) {
> +			struct vb2_buffer *vb2 = vb2_get_buffer(q, i);

videobuf2 usually names vb2_buffer variables just 'vb' (there's no
occurrence of 'vb2' in the existing code base). Could you rename this
and other variables in this patch ?

> +
> +			if (vb2->state == VB2_BUF_STATE_ACTIVE) {
>  				pr_warn("driver bug: stop_streaming operation is leaving buf %p in active state\n",
> -					q->bufs[i]);
> -				vb2_buffer_done(q->bufs[i], VB2_BUF_STATE_ERROR);
> +					vb2);
> +				vb2_buffer_done(vb2, VB2_BUF_STATE_ERROR);
>  			}
> +		}
>  		/* Must be zero now */
>  		WARN_ON(atomic_read(&q->owned_by_drv_count));
>  	}
> @@ -2061,7 +2066,7 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
>  	 * be changed, so we can't move the buf_finish() to __vb2_dqbuf().
>  	 */
>  	for (i = 0; i < q->num_buffers; ++i) {
> -		struct vb2_buffer *vb = q->bufs[i];
> +		struct vb2_buffer *vb = vb2_get_buffer(q, i);
>  		struct media_request *req = vb->req_obj.req;
>  
>  		/*
> @@ -2215,7 +2220,7 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long off,
>  	 * return its buffer and plane numbers.
>  	 */
>  	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
> -		vb = q->bufs[buffer];
> +		vb = vb2_get_buffer(q, buffer);
>  
>  		for (plane = 0; plane < vb->num_planes; ++plane) {
>  			if (vb->planes[plane].m.offset == off) {
> @@ -2262,7 +2267,7 @@ int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
>  		return -EINVAL;
>  	}
>  
> -	vb = q->bufs[index];
> +	vb = vb2_get_buffer(q, index);
>  
>  	if (plane >= vb->num_planes) {
>  		dprintk(q, 1, "buffer plane out of range\n");
> @@ -2339,7 +2344,7 @@ int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
>  	if (ret)
>  		goto unlock;
>  
> -	vb = q->bufs[buffer];
> +	vb = vb2_get_buffer(q, buffer);
>  
>  	/*
>  	 * MMAP requires page_aligned buffers.
> @@ -2679,7 +2684,7 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)
>  	 * Check if plane_count is correct
>  	 * (multiplane buffers are not supported).
>  	 */
> -	if (q->bufs[0]->num_planes != 1) {
> +	if (vb2_get_buffer(q, 0)->num_planes != 1) {

This may become problematic as there will be no guarantee going forward
that buffer 0 exists. Maybe it's fine for the fileio helpers though.

>  		ret = -EBUSY;
>  		goto err_reqbufs;
>  	}
> @@ -2688,12 +2693,14 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)
>  	 * Get kernel address of each buffer.
>  	 */
>  	for (i = 0; i < q->num_buffers; i++) {
> -		fileio->bufs[i].vaddr = vb2_plane_vaddr(q->bufs[i], 0);
> +		struct vb2_buffer *vb2 = vb2_get_buffer(q, i);
> +
> +		fileio->bufs[i].vaddr = vb2_plane_vaddr(vb2, 0);
>  		if (fileio->bufs[i].vaddr == NULL) {
>  			ret = -EINVAL;
>  			goto err_reqbufs;
>  		}
> -		fileio->bufs[i].size = vb2_plane_size(q->bufs[i], 0);
> +		fileio->bufs[i].size = vb2_plane_size(vb2, 0);
>  	}
>  
>  	/*
> @@ -2821,15 +2828,15 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
>  
>  		fileio->cur_index = index;
>  		buf = &fileio->bufs[index];
> -		b = q->bufs[index];
> +		b = vb2_get_buffer(q, index);
>  
>  		/*
>  		 * Get number of bytes filled by the driver
>  		 */
>  		buf->pos = 0;
>  		buf->queued = 0;
> -		buf->size = read ? vb2_get_plane_payload(q->bufs[index], 0)
> -				 : vb2_plane_size(q->bufs[index], 0);
> +		buf->size = read ? vb2_get_plane_payload(b, 0)
> +				 : vb2_plane_size(b, 0);
>  		/* Compensate for data_offset on read in the multiplanar case. */
>  		if (is_multiplanar && read &&
>  				b->planes[0].data_offset < buf->size) {
> @@ -2872,7 +2879,7 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
>  	 * Queue next buffer if required.
>  	 */
>  	if (buf->pos == buf->size || (!read && fileio->write_immediately)) {
> -		struct vb2_buffer *b = q->bufs[index];
> +		struct vb2_buffer *b = vb2_get_buffer(q, index);
>  
>  		/*
>  		 * Check if this is the last buffer to read.
> @@ -2899,7 +2906,7 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
>  		 */
>  		buf->pos = 0;
>  		buf->queued = 1;
> -		buf->size = vb2_plane_size(q->bufs[index], 0);
> +		buf->size = vb2_plane_size(vb2_get_buffer(q, index), 0);
>  		fileio->q_count += 1;
>  		/*
>  		 * If we are queuing up buffers for the first time, then
> @@ -2970,7 +2977,7 @@ static int vb2_thread(void *data)
>  		 * Call vb2_dqbuf to get buffer back.
>  		 */
>  		if (prequeue) {
> -			vb = q->bufs[index++];
> +			vb = vb2_get_buffer(q, index++);
>  			prequeue--;
>  		} else {
>  			call_void_qop(q, wait_finish, q);
> @@ -2979,7 +2986,7 @@ static int vb2_thread(void *data)
>  			call_void_qop(q, wait_prepare, q);
>  			dprintk(q, 5, "file io: vb2_dqbuf result: %d\n", ret);
>  			if (!ret)
> -				vb = q->bufs[index];
> +				vb = vb2_get_buffer(q, index);
>  		}
>  		if (ret || threadio->stop)
>  			break;
> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> index 1f5d235a8441..01b2bb957239 100644
> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> @@ -383,7 +383,7 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
>  		return -EINVAL;
>  	}
>  
> -	if (q->bufs[b->index] == NULL) {
> +	if (!vb2_get_buffer(q, b->index)) {
>  		/* Should never happen */
>  		dprintk(q, 1, "%s: buffer is NULL\n", opname);
>  		return -EINVAL;
> @@ -394,7 +394,7 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
>  		return -EINVAL;
>  	}
>  
> -	vb = q->bufs[b->index];
> +	vb = vb2_get_buffer(q, b->index);
>  	vbuf = to_vb2_v4l2_buffer(vb);
>  	ret = __verify_planes_array(vb, b);
>  	if (ret)
> @@ -628,11 +628,14 @@ static const struct vb2_buf_ops v4l2_buf_ops = {
>  struct vb2_buffer *vb2_find_buffer(struct vb2_queue *q, u64 timestamp)
>  {
>  	unsigned int i;
> +	struct vb2_buffer *vb2;
>  
> -	for (i = 0; i < q->num_buffers; i++)
> -		if (q->bufs[i]->copied_timestamp &&
> -		    q->bufs[i]->timestamp == timestamp)
> -			return vb2_get_buffer(q, i);
> +	for (i = 0; i < q->num_buffers; i++) {
> +		vb2 = vb2_get_buffer(q, i);
> +		if (vb2->copied_timestamp &&
> +		    vb2->timestamp == timestamp)
> +			return vb2;
> +	}
>  	return NULL;
>  }
>  EXPORT_SYMBOL_GPL(vb2_find_buffer);
> @@ -664,7 +667,7 @@ int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b)
>  		dprintk(q, 1, "buffer index out of range\n");
>  		return -EINVAL;
>  	}
> -	vb = q->bufs[b->index];
> +	vb = vb2_get_buffer(q, b->index);
>  	ret = __verify_planes_array(vb, b);
>  	if (!ret)
>  		vb2_core_querybuf(q, b->index, b);
> diff --git a/drivers/media/platform/amphion/vpu_dbg.c b/drivers/media/platform/amphion/vpu_dbg.c
> index 44b830ae01d8..8a423c1f6b55 100644
> --- a/drivers/media/platform/amphion/vpu_dbg.c
> +++ b/drivers/media/platform/amphion/vpu_dbg.c
> @@ -133,7 +133,7 @@ static int vpu_dbg_instance(struct seq_file *s, void *data)
>  
>  	vq = v4l2_m2m_get_src_vq(inst->fh.m2m_ctx);
>  	for (i = 0; i < vq->num_buffers; i++) {
> -		struct vb2_buffer *vb = vq->bufs[i];
> +		struct vb2_buffer *vb = vb2_get_buffer(vq, i);
>  		struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
>  
>  		if (vb->state == VB2_BUF_STATE_DEQUEUED)
> @@ -148,7 +148,7 @@ static int vpu_dbg_instance(struct seq_file *s, void *data)
>  
>  	vq = v4l2_m2m_get_dst_vq(inst->fh.m2m_ctx);
>  	for (i = 0; i < vq->num_buffers; i++) {
> -		struct vb2_buffer *vb = vq->bufs[i];
> +		struct vb2_buffer *vb = vb2_get_buffer(vq, i);
>  		struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
>  
>  		if (vb->state == VB2_BUF_STATE_DEQUEUED)
> diff --git a/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c b/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c
> index 969516a940ba..0be07f691d9a 100644
> --- a/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c
> +++ b/drivers/media/platform/mediatek/jpeg/mtk_jpeg_core.c
> @@ -603,7 +603,7 @@ static int mtk_jpeg_qbuf(struct file *file, void *priv, struct v4l2_buffer *buf)
>  		return -EINVAL;
>  	}
>  
> -	vb = vq->bufs[buf->index];
> +	vb = vb2_get_buffer(vq, buf->index);
>  	jpeg_src_buf = mtk_jpeg_vb2_to_srcbuf(vb);
>  	jpeg_src_buf->bs_size = buf->m.planes[0].bytesused;
>  
> diff --git a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_req_lat_if.c b/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_req_lat_if.c
> index cbb6728b8a40..f5958b6d834a 100644
> --- a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_req_lat_if.c
> +++ b/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_req_lat_if.c
> @@ -1701,7 +1701,7 @@ static int vdec_vp9_slice_setup_core_buffer(struct vdec_vp9_slice_instance *inst
>  
>  	/* update internal buffer's width/height */
>  	for (i = 0; i < vq->num_buffers; i++) {
> -		if (vb == vq->bufs[i]) {
> +		if (vb == vb2_get_buffer(vq, i)) {
>  			instance->dpb[i].width = w;
>  			instance->dpb[i].height = h;
>  			break;
> diff --git a/drivers/media/test-drivers/visl/visl-dec.c b/drivers/media/test-drivers/visl/visl-dec.c
> index 318d675e5668..328016b456ba 100644
> --- a/drivers/media/test-drivers/visl/visl-dec.c
> +++ b/drivers/media/test-drivers/visl/visl-dec.c
> @@ -290,13 +290,14 @@ static void visl_tpg_fill(struct visl_ctx *ctx, struct visl_run *run)
>  	for (i = 0; i < out_q->num_buffers; i++) {
>  		char entry[] = "index: %u, state: %s, request_fd: %d, ";
>  		u32 old_len = len;
> -		char *q_status = visl_get_vb2_state(out_q->bufs[i]->state);
> +		struct vb2_buffer *vb2 = vb2_get_buffer(out_q, i);
> +		char *q_status = visl_get_vb2_state(vb2->state);
>  
>  		len += scnprintf(&buf[len], TPG_STR_BUF_SZ - len,
>  				 entry, i, q_status,
> -				 to_vb2_v4l2_buffer(out_q->bufs[i])->request_fd);
> +				 to_vb2_v4l2_buffer(vb2)->request_fd);
>  
> -		len += visl_fill_bytesused(to_vb2_v4l2_buffer(out_q->bufs[i]),
> +		len += visl_fill_bytesused(to_vb2_v4l2_buffer(vb2),
>  					   &buf[len],
>  					   TPG_STR_BUF_SZ - len);
>  
> @@ -342,13 +343,14 @@ static void visl_tpg_fill(struct visl_ctx *ctx, struct visl_run *run)
>  	len = 0;
>  	for (i = 0; i < cap_q->num_buffers; i++) {
>  		u32 old_len = len;
> -		char *q_status = visl_get_vb2_state(cap_q->bufs[i]->state);
> +		struct vb2_buffer *vb2 = vb2_get_buffer(cap_q, i);
> +		char *q_status = visl_get_vb2_state(vb2->state);
>  
>  		len += scnprintf(&buf[len], TPG_STR_BUF_SZ - len,
>  				 "index: %u, status: %s, timestamp: %llu, is_held: %d",
> -				 cap_q->bufs[i]->index, q_status,
> -				 cap_q->bufs[i]->timestamp,
> -				 to_vb2_v4l2_buffer(cap_q->bufs[i])->is_held);
> +				 vb2->index, q_status,
> +				 vb2->timestamp,
> +				 to_vb2_v4l2_buffer(vb2)->is_held);
>  
>  		tpg_gen_text(&ctx->tpg, basep, line++ * line_height, 16, &buf[old_len]);
>  		frame_dprintk(ctx->dev, run->dst->sequence, "%s", &buf[old_len]);
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index 4b6a9d2ea372..d18c57e7aef0 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -1244,6 +1244,26 @@ static inline struct vb2_buffer *vb2_get_buffer(struct vb2_queue *q,
>  	return NULL;
>  }
>  
> +/**
> + * vb2_set_buffer() - set a buffer to a queue
> + * @q:	pointer to &struct vb2_queue with videobuf2 queue.
> + * @vb:	pointer to &struct vb2_buffer to be added to the queue.
> + */
> +static inline void vb2_set_buffer(struct vb2_queue *q, struct vb2_buffer *vb)
> +{
> +	q->bufs[vb->index] = vb;
> +}
> +
> +/**
> + * vb2_del_buffer() - remove a buffer from a queue
> + * @q:	pointer to &struct vb2_queue with videobuf2 queue.
> + * @vb:	pointer to &struct vb2_buffer to be removed from the queue.
> + */
> +static inline void vb2_del_buffer(struct vb2_queue *q, struct vb2_buffer *vb)
> +{
> +	q->bufs[vb->index] = NULL;
> +}
> +
>  /*
>   * The following functions are not part of the vb2 core API, but are useful
>   * functions for videobuf2-*.

-- 
Regards,

Laurent Pinchart

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