Re: [PATCH v21 7/9] media: v4l2: Add REMOVE_BUFS ioctl

[Benjamin Gaignard <benjamin.gaignard@collabora.com>]

Le 22/03/2024 à 08:54, Hans Verkuil a écrit :
> Hi Benjamin,
>
> I added the one additional sentence to vidioc-remove-bufs.rst as suggested
> by Mauro, and added his Reviewed/Acked-by lines.
>
> I'll merge this series on Monday after 6.9-rc1 has been released and then
> I will also merge the v4l-utils patches.
>
> No need for you to do anything.
>
> Thank you for all your work on this!

I happy to see this been merge soon.
Thanks lot for your time and your review.

Regards,
Benjamin

>
> 	Hans
>
> On 21/03/2024 4:03 pm, Mauro Carvalho Chehab wrote:
>> Em Thu, 21 Mar 2024 15:24:43 +0100
>> Hans Verkuil <hverkuil-cisco@xs4all.nl> escreveu:
>>
>>> On 21/03/2024 3:14 pm, Mauro Carvalho Chehab wrote:
>>>> Em Thu, 14 Mar 2024 16:32:24 +0100
>>>> Benjamin Gaignard <benjamin.gaignard@collabora.com> escreveu:
>>>>    
>>>>> VIDIOC_REMOVE_BUFS ioctl allows to remove buffers from a queue.
>>>>> The number of buffers to remove in given by count field of
>>>>> struct v4l2_remove_buffers and the range start at the index
>>>>> specified in the same structure.
>>>>>
>>>>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
>>>>> ---
>>>>> changes in version 21:
>>>>> - Be more careful about checking remove_bufs type field vs queue type.
>>>>> - Add documentation about type checking error.
>>>>> - Always set capabilities flags field.
>>>>>
>>>>>   .../userspace-api/media/v4l/user-func.rst     |  1 +
>>>>>   .../media/v4l/vidioc-remove-bufs.rst          | 85 +++++++++++++++++++
>>>>>   .../media/v4l/vidioc-reqbufs.rst              |  1 +
>>>>>   .../media/common/videobuf2/videobuf2-core.c   | 38 +++++++++
>>>>>   .../media/common/videobuf2/videobuf2-v4l2.c   | 20 ++++-
>>>>>   drivers/media/v4l2-core/v4l2-dev.c            |  3 +
>>>>>   drivers/media/v4l2-core/v4l2-ioctl.c          | 30 +++++++
>>>>>   include/media/v4l2-ioctl.h                    |  4 +
>>>>>   include/media/videobuf2-core.h                | 10 +++
>>>>>   include/media/videobuf2-v4l2.h                |  2 +
>>>>>   include/uapi/linux/videodev2.h                | 17 ++++
>>>>>   11 files changed, 210 insertions(+), 1 deletion(-)
>>>>>   create mode 100644 Documentation/userspace-api/media/v4l/vidioc-remove-bufs.rst
>>>>>
>>>>> diff --git a/Documentation/userspace-api/media/v4l/user-func.rst b/Documentation/userspace-api/media/v4l/user-func.rst
>>>>> index 15ff0bf7bbe6..6f661138801c 100644
>>>>> --- a/Documentation/userspace-api/media/v4l/user-func.rst
>>>>> +++ b/Documentation/userspace-api/media/v4l/user-func.rst
>>>>> @@ -62,6 +62,7 @@ Function Reference
>>>>>       vidioc-query-dv-timings
>>>>>       vidioc-querystd
>>>>>       vidioc-reqbufs
>>>>> +    vidioc-remove-bufs
>>>>>       vidioc-s-hw-freq-seek
>>>>>       vidioc-streamon
>>>>>       vidioc-subdev-enum-frame-interval
>>>>> diff --git a/Documentation/userspace-api/media/v4l/vidioc-remove-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-remove-bufs.rst
>>>>> new file mode 100644
>>>>> index 000000000000..0cbc8c7313b7
>>>>> --- /dev/null
>>>>> +++ b/Documentation/userspace-api/media/v4l/vidioc-remove-bufs.rst
>>>>> @@ -0,0 +1,85 @@
>>>>> +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
>>>>> +.. c:namespace:: V4L
>>>>> +
>>>>> +.. _VIDIOC_REMOVE_BUFS:
>>>>> +
>>>>> +************************
>>>>> +ioctl VIDIOC_REMOVE_BUFS
>>>>> +************************
>>>>> +
>>>>> +Name
>>>>> +====
>>>>> +
>>>>> +VIDIOC_REMOVE_BUFS - Removes buffers from a queue
>>>>> +
>>>>> +Synopsis
>>>>> +========
>>>>> +
>>>>> +.. c:macro:: VIDIOC_REMOVE_BUFS
>>>>> +
>>>>> +``int ioctl(int fd, VIDIOC_REMOVE_BUFS, struct v4l2_remove_buffers *argp)``
>>>>> +
>>>>> +Arguments
>>>>> +=========
>>>>> +
>>>>> +``fd``
>>>>> +    File descriptor returned by :c:func:`open()`.
>>>>> +
>>>>> +``argp``
>>>>> +    Pointer to struct :c:type:`v4l2_remove_buffers`.
>>>>> +
>>>>> +Description
>>>>> +===========
>>>>> +
>>>>> +Applications can optionally call the :ref:`VIDIOC_REMOVE_BUFS` ioctl to
>>>>> +remove buffers from a queue.
>>>>> +:ref:`VIDIOC_CREATE_BUFS` ioctl support is mandatory to enable :ref:`VIDIOC_REMOVE_BUFS`.
>>>>> +This ioctl is available if the ``V4L2_BUF_CAP_SUPPORTS_REMOVE_BUFS`` capability
>>>>> +is set on the queue when :c:func:`VIDIOC_REQBUFS` or :c:func:`VIDIOC_CREATE_BUFS`
>>>>> +are invoked.
>>>>> +
>>>>> +.. c:type:: v4l2_remove_buffers
>>>>> +
>>>>> +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
>>>>> +
>>>>> +.. flat-table:: struct v4l2_remove_buffers
>>>>> +    :header-rows:  0
>>>>> +    :stub-columns: 0
>>>>> +    :widths:       1 1 2
>>>>> +
>>>>> +    * - __u32
>>>>> +      - ``index``
>>>>> +      - The starting buffer index to remove. This field is ignored if count == 0.
>>>>> +    * - __u32
>>>>> +      - ``count``
>>>>> +      - The number of buffers to be removed with indices 'index' until 'index + count - 1'.
>>>>> +        All buffers in this range must be valid and in DEQUEUED state.
>>>>> +        :ref:`VIDIOC_REMOVE_BUFS` will always check the validity of ``type`, if it is
>>>>> +        invalid it returns ``EINVAL`` error code.
>>>>> +        If count is set to 0 :ref:`VIDIOC_REMOVE_BUFS` will do nothing and return 0.
>>>>> +    * - __u32
>>>>> +      - ``type``
>>>>> +      - Type of the stream or buffers, this is the same as the struct
>>>>> +	:c:type:`v4l2_format` ``type`` field. See
>>>>> +	:c:type:`v4l2_buf_type` for valid values.
>>>>> +    * - __u32
>>>>> +      - ``reserved``\ [13]
>>>>> +      - A place holder for future extensions. Drivers and applications
>>>>> +	must set the array to zero.
>>>>> +
>>>>> +Return Value
>>>>> +============
>>>>> +
>>>>> +On success 0 is returned, on error -1 and the ``errno`` variable is set
>>>>> +appropriately. The generic error codes are described at the
>>>>> +:ref:`Generic Error Codes <gen-errors>` chapter.
>>>> It is not enough to just return an error code. it should also describe
>>>> what will be the expected behavior after the call. Something like:
>>>>
>>>> 	If an error occurs, no buffers will be freed and one of the
>>>> 	error codes below will be returned:
>>> That's good to have. That is indeed not stated explicitly.
>>>
>>>>    
>>>>> +
>>>>> +EBUSY
>>>>> +    File I/O is in progress.
>>>>> +    One or more of the buffers in the range ``index`` to ``index + count - 1`` are not
>>>>> +    in DEQUEUED state.
>>>>> +
>>>>> +EINVAL
>>>>> +    One or more of the buffers in the range ``index`` to ``index + count - 1`` do not
>>>>> +    exist in the queue.
>>>>> +    The buffer type (``type`` field) is not valid.
>>>> IMO, it needs also another error code: as there's a minimal number of
>>>> buffers to be queued (let's say, 2), what happens if there are currently
>>>> 3 buffers allocated and an ioctl is called to free 2 buffers?
>>>>
>>>> IMO, it shall return an error code and not free any buffers.
>>> Note the requirement that all buffers you want to remove have to be in dequeued
>>> state. So you can never remove buffers that are still in flight. An attempt to
>>> do that results in EBUSY.
>>>
>>> So there is no need for an other error code.
>>>
>>>> The best would be to return a code different than EINVAL. Maybe E2BIG?
>>>>    
>>>>> diff --git a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
>>>>> index 0b3a41a45d05..bbc22dd76032 100644
>>>>> --- a/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
>>>>> +++ b/Documentation/userspace-api/media/v4l/vidioc-reqbufs.rst
>>>>> @@ -121,6 +121,7 @@ aborting or finishing any DMA in progress, an implicit
>>>>>   .. _V4L2-BUF-CAP-SUPPORTS-M2M-HOLD-CAPTURE-BUF:
>>>>>   .. _V4L2-BUF-CAP-SUPPORTS-MMAP-CACHE-HINTS:
>>>>>   .. _V4L2-BUF-CAP-SUPPORTS-MAX-NUM-BUFFERS:
>>>>> +.. _V4L2-BUF-CAP-SUPPORTS-REMOVE-BUFS:
>>>>>   
>>>>>   .. raw:: latex
>>>>>   
>>>>> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
>>>>> index 009cea95d662..0b2b48e1b2df 100644
>>>>> --- a/drivers/media/common/videobuf2/videobuf2-core.c
>>>>> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
>>>>> @@ -1691,6 +1691,44 @@ int vb2_core_prepare_buf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb)
>>>>>   }
>>>>>   EXPORT_SYMBOL_GPL(vb2_core_prepare_buf);
>>>>>   
>>>>> +int vb2_core_remove_bufs(struct vb2_queue *q, unsigned int start, unsigned int count)
>>>>> +{
>>>>> +	unsigned int i, ret = 0;
>>>>> +	unsigned int q_num_bufs = vb2_get_num_buffers(q);
>>>>> +
>>>>> +	if (count == 0)
>>>>> +		return 0;
>>>>> +
>>>>> +	if (count > q_num_bufs)
>>>>> +		return -EINVAL;
>>>> It also needs:
>>>>
>>>> 	if (q_num_bufs - count < q->min_reqbufs_allocation && q_num_bufs != count)
>>>> 		return <some error code>;
>>>>
>>>> e. g. it shall not accept keeping, for instance, just one buffer allocated.
>>> That's perfectly fine. The min_reqbufs_allocation is specific to VIDIOC_REQBUFS
>>> (hence the name). If you use CREATE_BUFS/REMOVE_BUFS, then you are fully responsible
>>> for allocating and removing buffers.
>>>
>>> This is something that was discussed in earlier revisions of this series.
>>>
>>> It is actually rather ugly that REQBUFS does this, but we need to keep that behavior
>>> since that's how REQBUFS worked historically.
>>>
>>> VIDIOC_CREATE_BUFS was never affected by this, so if you want to allocate N
>>> buffers with CREATE_BUFS, then you'll never get more than N buffers (you might get
>>> less, of course).
>> OK.
>>
>> So, after doing the documentation change, feel free to add:
>>
>> Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
>>
>>> Regards,
>>>
>>> 	Hans
>>>
>>>>    
>>>>> +
>>>>> +	if (start > q->max_num_buffers - count)
>>>>> +		return -EINVAL;
>>>>> +
>>>>> +	mutex_lock(&q->mmap_lock);
>>>>> +
>>>>> +	/* Check that all buffers in the range exist */
>>>>> +	for (i = start; i < start + count; i++) {
>>>>> +		struct vb2_buffer *vb = vb2_get_buffer(q, i);
>>>>> +
>>>>> +		if (!vb) {
>>>>> +			ret = -EINVAL;
>>>>> +			goto unlock;
>>>>> +		}
>>>>> +		if (vb->state != VB2_BUF_STATE_DEQUEUED) {
>>>>> +			ret = -EBUSY;
>>>>> +			goto unlock;
>>>>> +		}
>>>>> +	}
>>>>> +	__vb2_queue_free(q, start, count);
>>>>> +	dprintk(q, 2, "%u buffers removed\n", count);
>>>>> +
>>>>> +unlock:
>>>>> +	mutex_unlock(&q->mmap_lock);
>>>>> +	return ret;
>>>>> +}
>>>>> +EXPORT_SYMBOL_GPL(vb2_core_remove_bufs);
>>>>> +
>>>>>   /*
>>>>>    * vb2_start_streaming() - Attempt to start streaming.
>>>>>    * @q:		videobuf2 queue
>>>>> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
>>>>> index 03e8080a68a8..293f3d5f1c4e 100644
>>>>> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
>>>>> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
>>>>> @@ -685,7 +685,7 @@ static void vb2_set_flags_and_caps(struct vb2_queue *q, u32 memory,
>>>>>   		*flags &= V4L2_MEMORY_FLAG_NON_COHERENT;
>>>>>   	}
>>>>>   
>>>>> -	*caps = V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS;
>>>>> +	*caps |= V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS;
>>>>>   	if (q->io_modes & VB2_MMAP)
>>>>>   		*caps |= V4L2_BUF_CAP_SUPPORTS_MMAP;
>>>>>   	if (q->io_modes & VB2_USERPTR)
>>>>> @@ -1001,6 +1001,24 @@ EXPORT_SYMBOL_GPL(vb2_poll);
>>>>>   
>>>>>   /* vb2 ioctl helpers */
>>>>>   
>>>>> +int vb2_ioctl_remove_bufs(struct file *file, void *priv,
>>>>> +			  struct v4l2_remove_buffers *d)
>>>>> +{
>>>>> +	struct video_device *vdev = video_devdata(file);
>>>>> +
>>>>> +	if (vdev->queue->type != d->type)
>>>>> +		return -EINVAL;
>>>>> +
>>>>> +	if (d->count == 0)
>>>>> +		return 0;
>>>>> +
>>>>> +	if (vb2_queue_is_busy(vdev->queue, file))
>>>>> +		return -EBUSY;
>>>>> +
>>>>> +	return vb2_core_remove_bufs(vdev->queue, d->index, d->count);
>>>>> +}
>>>>> +EXPORT_SYMBOL_GPL(vb2_ioctl_remove_bufs);
>>>>> +
>>>>>   int vb2_ioctl_reqbufs(struct file *file, void *priv,
>>>>>   			  struct v4l2_requestbuffers *p)
>>>>>   {
>>>>> diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
>>>>> index d13954bd31fd..e39e9742fdb5 100644
>>>>> --- a/drivers/media/v4l2-core/v4l2-dev.c
>>>>> +++ b/drivers/media/v4l2-core/v4l2-dev.c
>>>>> @@ -722,6 +722,9 @@ static void determine_valid_ioctls(struct video_device *vdev)
>>>>>   		SET_VALID_IOCTL(ops, VIDIOC_PREPARE_BUF, vidioc_prepare_buf);
>>>>>   		SET_VALID_IOCTL(ops, VIDIOC_STREAMON, vidioc_streamon);
>>>>>   		SET_VALID_IOCTL(ops, VIDIOC_STREAMOFF, vidioc_streamoff);
>>>>> +		/* VIDIOC_CREATE_BUFS support is mandatory to enable VIDIOC_REMOVE_BUFS */
>>>>> +		if (ops->vidioc_create_bufs)
>>>>> +			SET_VALID_IOCTL(ops, VIDIOC_REMOVE_BUFS, vidioc_remove_bufs);
>>>>>   	}
>>>>>   
>>>>>   	if (is_vid || is_vbi || is_meta) {
>>>>> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
>>>>> index 6e7b8b682d13..5aeff5519407 100644
>>>>> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
>>>>> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
>>>>> @@ -489,6 +489,14 @@ static void v4l_print_create_buffers(const void *arg, bool write_only)
>>>>>   	v4l_print_format(&p->format, write_only);
>>>>>   }
>>>>>   
>>>>> +static void v4l_print_remove_buffers(const void *arg, bool write_only)
>>>>> +{
>>>>> +	const struct v4l2_remove_buffers *p = arg;
>>>>> +
>>>>> +	pr_cont("type=%s, index=%u, count=%u\n",
>>>>> +		prt_names(p->type, v4l2_type_names), p->index, p->count);
>>>>> +}
>>>>> +
>>>>>   static void v4l_print_streamparm(const void *arg, bool write_only)
>>>>>   {
>>>>>   	const struct v4l2_streamparm *p = arg;
>>>>> @@ -2092,6 +2100,7 @@ static int v4l_overlay(const struct v4l2_ioctl_ops *ops,
>>>>>   static int v4l_reqbufs(const struct v4l2_ioctl_ops *ops,
>>>>>   				struct file *file, void *fh, void *arg)
>>>>>   {
>>>>> +	struct video_device *vfd = video_devdata(file);
>>>>>   	struct v4l2_requestbuffers *p = arg;
>>>>>   	int ret = check_fmt(file, p->type);
>>>>>   
>>>>> @@ -2100,6 +2109,10 @@ static int v4l_reqbufs(const struct v4l2_ioctl_ops *ops,
>>>>>   
>>>>>   	memset_after(p, 0, flags);
>>>>>   
>>>>> +	p->capabilities = 0;
>>>>> +	if (is_valid_ioctl(vfd, VIDIOC_REMOVE_BUFS))
>>>>> +		p->capabilities = V4L2_BUF_CAP_SUPPORTS_REMOVE_BUFS;
>>>>> +
>>>>>   	return ops->vidioc_reqbufs(file, fh, p);
>>>>>   }
>>>>>   
>>>>> @@ -2133,6 +2146,7 @@ static int v4l_dqbuf(const struct v4l2_ioctl_ops *ops,
>>>>>   static int v4l_create_bufs(const struct v4l2_ioctl_ops *ops,
>>>>>   				struct file *file, void *fh, void *arg)
>>>>>   {
>>>>> +	struct video_device *vfd = video_devdata(file);
>>>>>   	struct v4l2_create_buffers *create = arg;
>>>>>   	int ret = check_fmt(file, create->format.type);
>>>>>   
>>>>> @@ -2143,6 +2157,10 @@ static int v4l_create_bufs(const struct v4l2_ioctl_ops *ops,
>>>>>   
>>>>>   	v4l_sanitize_format(&create->format);
>>>>>   
>>>>> +	create->capabilities = 0;
>>>>> +	if (is_valid_ioctl(vfd, VIDIOC_REMOVE_BUFS))
>>>>> +		create->capabilities = V4L2_BUF_CAP_SUPPORTS_REMOVE_BUFS;
>>>>> +
>>>>>   	ret = ops->vidioc_create_bufs(file, fh, create);
>>>>>   
>>>>>   	if (create->format.type == V4L2_BUF_TYPE_VIDEO_CAPTURE ||
>>>>> @@ -2161,6 +2179,17 @@ static int v4l_prepare_buf(const struct v4l2_ioctl_ops *ops,
>>>>>   	return ret ? ret : ops->vidioc_prepare_buf(file, fh, b);
>>>>>   }
>>>>>   
>>>>> +static int v4l_remove_bufs(const struct v4l2_ioctl_ops *ops,
>>>>> +			   struct file *file, void *fh, void *arg)
>>>>> +{
>>>>> +	struct v4l2_remove_buffers *remove = arg;
>>>>> +
>>>>> +	if (ops->vidioc_remove_bufs)
>>>>> +		return ops->vidioc_remove_bufs(file, fh, remove);
>>>>> +
>>>>> +	return -ENOTTY;
>>>>> +}
>>>>> +
>>>>>   static int v4l_g_parm(const struct v4l2_ioctl_ops *ops,
>>>>>   				struct file *file, void *fh, void *arg)
>>>>>   {
>>>>> @@ -2910,6 +2939,7 @@ static const struct v4l2_ioctl_info v4l2_ioctls[] = {
>>>>>   	IOCTL_INFO(VIDIOC_ENUM_FREQ_BANDS, v4l_enum_freq_bands, v4l_print_freq_band, 0),
>>>>>   	IOCTL_INFO(VIDIOC_DBG_G_CHIP_INFO, v4l_dbg_g_chip_info, v4l_print_dbg_chip_info, INFO_FL_CLEAR(v4l2_dbg_chip_info, match)),
>>>>>   	IOCTL_INFO(VIDIOC_QUERY_EXT_CTRL, v4l_query_ext_ctrl, v4l_print_query_ext_ctrl, INFO_FL_CTRL | INFO_FL_CLEAR(v4l2_query_ext_ctrl, id)),
>>>>> +	IOCTL_INFO(VIDIOC_REMOVE_BUFS, v4l_remove_bufs, v4l_print_remove_buffers, INFO_FL_PRIO | INFO_FL_QUEUE | INFO_FL_CLEAR(v4l2_remove_buffers, type)),
>>>>>   };
>>>>>   #define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls)
>>>>>   
>>>>> diff --git a/include/media/v4l2-ioctl.h b/include/media/v4l2-ioctl.h
>>>>> index edb733f21604..bdbb7e542321 100644
>>>>> --- a/include/media/v4l2-ioctl.h
>>>>> +++ b/include/media/v4l2-ioctl.h
>>>>> @@ -163,6 +163,8 @@ struct v4l2_fh;
>>>>>    *	:ref:`VIDIOC_CREATE_BUFS <vidioc_create_bufs>` ioctl
>>>>>    * @vidioc_prepare_buf: pointer to the function that implements
>>>>>    *	:ref:`VIDIOC_PREPARE_BUF <vidioc_prepare_buf>` ioctl
>>>>> + * @vidioc_remove_bufs: pointer to the function that implements
>>>>> + *	:ref:`VIDIOC_REMOVE_BUFS <vidioc_remove_bufs>` ioctl
>>>>>    * @vidioc_overlay: pointer to the function that implements
>>>>>    *	:ref:`VIDIOC_OVERLAY <vidioc_overlay>` ioctl
>>>>>    * @vidioc_g_fbuf: pointer to the function that implements
>>>>> @@ -422,6 +424,8 @@ struct v4l2_ioctl_ops {
>>>>>   				  struct v4l2_create_buffers *b);
>>>>>   	int (*vidioc_prepare_buf)(struct file *file, void *fh,
>>>>>   				  struct v4l2_buffer *b);
>>>>> +	int (*vidioc_remove_bufs)(struct file *file, void *fh,
>>>>> +				  struct v4l2_remove_buffers *d);
>>>>>   
>>>>>   	int (*vidioc_overlay)(struct file *file, void *fh, unsigned int i);
>>>>>   	int (*vidioc_g_fbuf)(struct file *file, void *fh,
>>>>> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
>>>>> index b9333e2c7797..955237ac503d 100644
>>>>> --- a/include/media/videobuf2-core.h
>>>>> +++ b/include/media/videobuf2-core.h
>>>>> @@ -870,6 +870,16 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
>>>>>    */
>>>>>   int vb2_core_prepare_buf(struct vb2_queue *q, struct vb2_buffer *vb, void *pb);
>>>>>   
>>>>> +/**
>>>>> + * vb2_core_remove_bufs() -
>>>>> + * @q:		pointer to &struct vb2_queue with videobuf2 queue.
>>>>> + * @start:	first index of the range of buffers to remove.
>>>>> + * @count:	number of buffers to remove.
>>>>> + *
>>>>> + *  Return: returns zero on success; an error code otherwise.
>>>>> + */
>>>>> +int vb2_core_remove_bufs(struct vb2_queue *q, unsigned int start, unsigned int count);
>>>>> +
>>>>>   /**
>>>>>    * vb2_core_qbuf() - Queue a buffer from userspace
>>>>>    *
>>>>> diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h
>>>>> index 5a845887850b..77ce8238ab30 100644
>>>>> --- a/include/media/videobuf2-v4l2.h
>>>>> +++ b/include/media/videobuf2-v4l2.h
>>>>> @@ -334,6 +334,8 @@ int vb2_ioctl_streamon(struct file *file, void *priv, enum v4l2_buf_type i);
>>>>>   int vb2_ioctl_streamoff(struct file *file, void *priv, enum v4l2_buf_type i);
>>>>>   int vb2_ioctl_expbuf(struct file *file, void *priv,
>>>>>   	struct v4l2_exportbuffer *p);
>>>>> +int vb2_ioctl_remove_bufs(struct file *file, void *priv,
>>>>> +			  struct v4l2_remove_buffers *p);
>>>>>   
>>>>>   /* struct v4l2_file_operations helpers */
>>>>>   
>>>>> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>>>>> index a8015e5e7fa4..2663213b76a4 100644
>>>>> --- a/include/uapi/linux/videodev2.h
>>>>> +++ b/include/uapi/linux/videodev2.h
>>>>> @@ -1036,6 +1036,7 @@ struct v4l2_requestbuffers {
>>>>>   #define V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF	(1 << 5)
>>>>>   #define V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS		(1 << 6)
>>>>>   #define V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS		(1 << 7)
>>>>> +#define V4L2_BUF_CAP_SUPPORTS_REMOVE_BUFS		(1 << 8)
>>>>>   
>>>>>   /**
>>>>>    * struct v4l2_plane - plane info for multi-planar buffers
>>>>> @@ -2624,6 +2625,20 @@ struct v4l2_create_buffers {
>>>>>   	__u32			reserved[5];
>>>>>   };
>>>>>   
>>>>> +/**
>>>>> + * struct v4l2_remove_buffers - VIDIOC_REMOVE_BUFS argument
>>>>> + * @index:	the first buffer to be removed
>>>>> + * @count:	number of buffers to removed
>>>>> + * @type:	enum v4l2_buf_type
>>>>> + * @reserved:	future extensions
>>>>> + */
>>>>> +struct v4l2_remove_buffers {
>>>>> +	__u32			index;
>>>>> +	__u32			count;
>>>>> +	__u32			type;
>>>>> +	__u32			reserved[13];
>>>>> +};
>>>>> +
>>>>>   /*
>>>>>    *	I O C T L   C O D E S   F O R   V I D E O   D E V I C E S
>>>>>    *
>>>>> @@ -2723,6 +2738,8 @@ struct v4l2_create_buffers {
>>>>>   #define VIDIOC_DBG_G_CHIP_INFO  _IOWR('V', 102, struct v4l2_dbg_chip_info)
>>>>>   
>>>>>   #define VIDIOC_QUERY_EXT_CTRL	_IOWR('V', 103, struct v4l2_query_ext_ctrl)
>>>>> +#define VIDIOC_REMOVE_BUFS	_IOWR('V', 104, struct v4l2_remove_buffers)
>>>>> +
>>>>>   
>>>>>   /* Reminder: when adding new ioctls please add support for them to
>>>>>      drivers/media/v4l2-core/v4l2-compat-ioctl32.c as well! */
>>>>
>>>>
>>>> Thanks,
>>>> Mauro
>>
>>
>> Thanks,
>> Mauro
>>
>