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Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qdXBx-006CGn-2A; Tue, 05 Sep 2023 14:38:09 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qdXBs-006CF0-0U; Tue, 05 Sep 2023 14:38:08 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A9EC0B811F5; Tue, 5 Sep 2023 14:38:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 44EF0C433C8; Tue, 5 Sep 2023 14:37:58 +0000 (UTC) Message-ID: Date: Tue, 5 Sep 2023 16:37:56 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v6 17/18] media: v4l2: Add DELETE_BUFS ioctl Content-Language: en-US, nl To: Benjamin Gaignard , mchehab@kernel.org, tfiga@chromium.org, m.szyprowski@samsung.com, ming.qian@nxp.com, ezequiel@vanguardiasur.com.ar, p.zabel@pengutronix.de, gregkh@linuxfoundation.org, nicolas.dufresne@collabora.com Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-staging@lists.linux.dev, kernel@collabora.com References: <20230901124414.48497-1-benjamin.gaignard@collabora.com> <20230901124414.48497-18-benjamin.gaignard@collabora.com> <814130d1-8597-d567-ddea-cb82cadea00f@xs4all.nl> <294f4150-cbae-f71b-9804-f985d0b0492a@collabora.com> From: Hans Verkuil In-Reply-To: <294f4150-cbae-f71b-9804-f985d0b0492a@collabora.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230905_073804_468961_63D9108F X-CRM114-Status: GOOD ( 48.41 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org Hi Benjamin, On 05/09/2023 16:28, Benjamin Gaignard wrote: > > Le 05/09/2023 à 10:17, Hans Verkuil a écrit : >> On 01/09/2023 14:44, Benjamin Gaignard wrote: >>> VIDIOC_DELETE_BUFS ioctl allows to delete buffers from a queue. >>> The number of buffers to delete in given by count field of >>> struct v4l2_delete_buffers and the range start at the index >>> specified in the same structure. >>> >>> Signed-off-by: Benjamin Gaignard >>> --- >>> v6: >>> - Add lock in vb2_core_delete_buf() >>> - Fix typo and comments >>> - Add flags in VIDIOC_DELETE_BUFS decalaration >>> >>>   .../userspace-api/media/v4l/user-func.rst     |  1 + >>>   .../media/v4l/vidioc-delete-bufs.rst          | 73 +++++++++++++++++++ >>>   .../media/common/videobuf2/videobuf2-core.c   | 24 ++++++ >>>   .../media/common/videobuf2/videobuf2-v4l2.c   | 38 +++++++++- >>>   drivers/media/v4l2-core/v4l2-dev.c            |  1 + >>>   drivers/media/v4l2-core/v4l2-ioctl.c          | 17 +++++ >>>   include/media/v4l2-ioctl.h                    |  4 + >>>   include/media/videobuf2-core.h                |  9 +++ >>>   include/media/videobuf2-v4l2.h                | 11 +++ >>>   include/uapi/linux/videodev2.h                | 16 ++++ >>>   10 files changed, 193 insertions(+), 1 deletion(-) >>>   create mode 100644 Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst >>> >>> diff --git a/Documentation/userspace-api/media/v4l/user-func.rst b/Documentation/userspace-api/media/v4l/user-func.rst >>> index 15ff0bf7bbe6..3fd567695477 100644 >>> --- a/Documentation/userspace-api/media/v4l/user-func.rst >>> +++ b/Documentation/userspace-api/media/v4l/user-func.rst >>> @@ -17,6 +17,7 @@ Function Reference >>>       vidioc-dbg-g-chip-info >>>       vidioc-dbg-g-register >>>       vidioc-decoder-cmd >>> +    vidioc-delete-bufs >>>       vidioc-dqevent >>>       vidioc-dv-timings-cap >>>       vidioc-encoder-cmd >>> diff --git a/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst b/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst >>> new file mode 100644 >>> index 000000000000..a55fe6331fc8 >>> --- /dev/null >>> +++ b/Documentation/userspace-api/media/v4l/vidioc-delete-bufs.rst >>> @@ -0,0 +1,73 @@ >>> +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later >>> +.. c:namespace:: V4L >>> + >>> +.. _VIDIOC_DELETE_BUFS: >>> + >>> +************************ >>> +ioctl VIDIOC_DELETE_BUFS >>> +************************ >>> + >>> +Name >>> +==== >>> + >>> +VIDIOC_DELETE_BUFS - Deletes buffers from a queue >>> + >>> +Synopsis >>> +======== >>> + >>> +.. c:macro:: VIDIOC_DELETE_BUFs >>> + >>> +``int ioctl(int fd, VIDIOC_DELETE_BUFs, struct v4l2_delete_buffers *argp)`` >>> + >>> +Arguments >>> +========= >>> + >>> +``fd`` >>> +    File descriptor returned by :c:func:`open()`. >>> + >>> +``argp`` >>> +    Pointer to struct :c:type:`v4l2_delete_buffers`. >>> + >>> +Description >>> +=========== >>> + >>> +Applications can optionally call the :ref:`VIDIOC_DELETE_BUFS` ioctl to >>> +delete buffers from a queue. >>> + >>> +.. c:type:: v4l2_delete_buffers >>> + >>> +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}| >>> + >>> +.. flat-table:: struct v4l2_delete_buffers >>> +    :header-rows:  0 >>> +    :stub-columns: 0 >>> +    :widths:       1 1 2 >>> + >>> +    * - __u32 >>> +      - ``index`` >>> +      - The starting buffer index to delete. >>> +    * - __u32 >>> +      - ``count`` >>> +      - The number of buffers to be deleted. >> That's not quite correct. This function will delete the buffers with indices >> index until index+count-1. And indices in that range have to be valid buffers, >> i.e. you can't have already deleted buffers in that range. >> >> Or should we allow that? It is a fair question. >> >> All buffers also have to be in the DEQUEUED state. >> >> The text above suggests that given the following valid indices: >> >> 0, 1, 3, 4 (so the buffer with index 2 was already deleted) >> >> deleting 2 buffers from index 1 would delete buffers 1, 3. When in >> fact it will attempt to delete buffers 1 and 2. >> >> Also document explicitly that calling this with count=0 (and perhaps >> index=0 as well?) can be used to check if this ioctl is supported. > > I will do that. > >> >>> +    * - __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. >> What should happen if you delete ALL buffers with this call? I.e., the >> equivalent to REQBUFS with count=0. >> >> Thinking about this the main difference is that DELETE_BUFS can only delete >> dequeued buffers and it does not stop streaming if all buffers are deleted. >> >> So REQBUFS with count=0 (or a STREAMOFF) is still needed to officially stop >> streaming and cancel the queue. >> >> Basically REQBUFS with count=0 is almost the equivalent of calling STREAMOFF followed >> by DELETE_BUFS for all buffers. Almost, but not quite: REQBUFS(0) also reports >> if the queue is unbalanced, and it sets q->num_buffers to 0. And in vb2_ioctl_reqbufs >> it will set vdev->queue->owner to NULL. >> >> I am inclined to do the same if DELETE_BUFS deletes all buffers. > > Unlike REQBUFS DELETE_BUFS can delete buffers while streaming so for me the ownership > should not change even if there is no more dequeued buffers. > For REQBUFS with count=0 means that the going stream is stopped so we can delete all the buffers > while DELETE_BUFS usage is to delete buffers while keeping the stream alive. I'm undecided on this. It's something we can decide later. > >> >>> + >>> +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 ` chapter. >>> + >>> +EBUSY >>> +    File I/O is in progress. >>> + >>> +EINVAL >>> +    The buffer ``index`` doesn't exist in the queue. >>> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c >>> index dc7f6b59d237..9edb2a1e95fc 100644 >>> --- a/drivers/media/common/videobuf2/videobuf2-core.c >>> +++ b/drivers/media/common/videobuf2/videobuf2-core.c >>> @@ -1633,6 +1633,30 @@ 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_delete_buf(struct vb2_queue *q, struct vb2_buffer *vb) >>> +{ >>> +    mutex_lock(&q->mmap_lock); >>> +    if (vb->planes[0].mem_priv) >>> +        call_void_vb_qop(vb, buf_cleanup, vb); >>> + >>> +    /* Free MMAP buffers or release USERPTR buffers */ >>> +    if (q->memory == VB2_MEMORY_MMAP) >>> +        __vb2_buf_mem_free(vb); >>> +    else if (q->memory == VB2_MEMORY_DMABUF) >>> +        __vb2_buf_dmabuf_put(vb); >>> +    else >>> +        __vb2_buf_userptr_put(vb); >>> + >>> +    vb2_queue_remove_buffer(q, vb); >>> +    mutex_unlock(&q->mmap_lock); >>> + >>> +    dprintk(q, 2, "buffer %d deleted\n", vb->index); >>> +    kfree(vb); >>> + >>> +    return 0; >>> +} >>> +EXPORT_SYMBOL_GPL(vb2_core_delete_buf); >> This is duplicating what already happens in __vb2_free_mem and __vb2_queue_free. >> >> That code needs to be refactored. >> >> What you want is a __vb2_delete_buffers(struct vb2_queue *q, unsigned int index, unsigned int buffers) >> function that is called with mmap_lock held and that deletes buffers in the range 'index' >> to 'index + count - 1'. Buffers may already be deleted. >> >> __vb2_free_mem does almost do all of that already. >> >> Then this new function can be called from __vb2_queue_free() and you can make >> a vb2_core_delete_bufs() function that takes the lock and calls __vb2_delete_buffers. >> >> Another note: currently __vb2_queue_free checks if any of the buffers had unbalanced >> operations. That check needs to be moved to __vb2_delete_buffers as well otherwise >> that would never be reported when using DELETE_BUFS. > > Loops in __vb2_queue_free() and __vb2_free_mem() try to delete buffers at the end of the > queue, I could just modify these functions prototype and loops to start from a given index. > That should do the job but have impact on create_bufs (see below) > >> >>> + >>>   /* >>>    * 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 8ba658ad9891..d0098f58a65c 100644 >>> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c >>> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c >>> @@ -385,7 +385,7 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md >>>         vb = vb2_get_buffer(q, b->index); >>>       if (!vb) { >>> -        dprintk(q, 1, "%s: buffer is NULL\n", opname); >>> +        dprintk(q, 1, "%s: buffer %u was deleted\n", opname, b->index); >>>           return -EINVAL; >>>       } >>>   @@ -757,6 +757,42 @@ int vb2_prepare_buf(struct vb2_queue *q, struct media_device *mdev, >>>   } >>>   EXPORT_SYMBOL_GPL(vb2_prepare_buf); >>>   +int vb2_delete_bufs(struct vb2_queue *q, struct v4l2_delete_buffers *d) >>> +{ >>> +    struct vb2_buffer *vb; >>> +    unsigned int index; >>> +    int ret = 0; >>> + >> Add: >> >>     if (!d->count) >>         return 0; >> >> (possibly also check if !d->index) >> >>> +    if (d->index > q->num_buffers || >>> should be >= here. >>> +        d->count > q->num_buffers || >>> +        (d->index + d->count) > q->num_buffers) { >>> +        return -EINVAL; >>> +    } >> Once we can delete buffers, how does that change the meaning of num_buffers? >> Isn't this really max_buffer_index or something similar? But we probably also >> still need to keep track of the actual number of buffers. >> >> And create_bufs still allocated buffers from the last index onwards, it does >> not attempt to reuse indices of previously deleted buffers. > > Reuse previous indices require to be sure that a range of index is free because > create_bufs returns, in index parameter, the starting buffer index. > I will add a function to find the first available range and use it in vb2_create_bufs() > to change how create->index is set. > Hans, sound good for you ? That's what I had in mind. It is an option to keep a bitmap to keep track of which buffer indices are in use. You could use bitmap_find_next_zero_area to find the free range. Just an option. > >> >> There are a lot of drivers that use num_buffers, they will have to be audited. >> >> This needs a lot more thought. >> >>> + >>> +    for (index = d->index; index < d->index + d->count; index++) { >>> +        vb = vb2_get_buffer(q, index); >>> +        if (!vb) { >>> +            dprintk(q, 1, "can't find the requested buffer\n"); >>> +            ret = -EINVAL; >>> +            goto error; >>> +        } >>> +        if (vb->state != VB2_BUF_STATE_DEQUEUED) { >>> +            dprintk(q, 1, "can't delete non dequeued buffer index %d\n", vb->index); >>> +            ret = -EINVAL; >>> +            goto error; >>> +        } >> These checks have to take place first, then, if all is OK, you call vb2_core_delete_bufs. >> >> Actually, thinking this over, I would move all these checks to vb2_core_delete_bufs. >> >> It can all be put under the mmap_lock mutex to ensure nobody is messing around >> with the queue while this takes place. >> >> Note that when vb2_core_reqbufs() is called with count=0, then if it sees that >> a buffer is still in use (mmaped), it will log a debug message that the buffers >> are orphaned. We should keep that, I believe. >> >>> + >>> +        ret = vb2_core_delete_buf(q, vb); >>> +        if (ret) >>> +            break; >>> +    } >>> + >>> +error: >>> +    d->index = index; >> I wouldn't do this. I don't think this is useful. >> >>> +    return ret; >>> +} >>> +EXPORT_SYMBOL_GPL(vb2_delete_bufs); >>> + >>>   int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create) >>>   { >>>       unsigned requested_planes = 1; >>> diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c >>> index f81279492682..215654fd6581 100644 >>> --- a/drivers/media/v4l2-core/v4l2-dev.c >>> +++ b/drivers/media/v4l2-core/v4l2-dev.c >>> @@ -720,6 +720,7 @@ 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); >>> +        SET_VALID_IOCTL(ops, VIDIOC_DELETE_BUFS, vidioc_delete_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 f4d9d6279094..aac3a0ea0126 100644 >>> --- a/drivers/media/v4l2-core/v4l2-ioctl.c >>> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c >>> @@ -489,6 +489,13 @@ static void v4l_print_create_buffers(const void *arg, bool write_only) >>>       v4l_print_format(&p->format, write_only); >>>   } >>>   +static void v4l_print_delete_buffers(const void *arg, bool write_only) >>> +{ >>> +    const struct v4l2_delete_buffers *p = arg; >>> + >>> +    pr_cont("index=%d, count=%d\n", p->index, p->count); >> Use %u since both args are unsigned. >> >>> +} >>> + >>>   static void v4l_print_streamparm(const void *arg, bool write_only) >>>   { >>>       const struct v4l2_streamparm *p = arg; >>> @@ -2160,6 +2167,15 @@ static int v4l_prepare_buf(const struct v4l2_ioctl_ops *ops, >>>       return ret ? ret : ops->vidioc_prepare_buf(file, fh, b); >>>   } >>>   +static int v4l_delete_bufs(const struct v4l2_ioctl_ops *ops, >>> +               struct file *file, void *fh, void *arg) >>> +{ >>> +    struct v4l2_delete_buffers *delete = arg; >>> +    int ret = check_fmt(file, delete->type); >>> + >>> +    return ret ? ret : ops->vidioc_delete_bufs(file, fh, delete); >>> +} >>> + >>>   static int v4l_g_parm(const struct v4l2_ioctl_ops *ops, >>>                   struct file *file, void *fh, void *arg) >>>   { >>> @@ -2909,6 +2925,7 @@ 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_DELETE_BUFS, v4l_delete_bufs, v4l_print_delete_buffers, INFO_FL_PRIO | INFO_FL_QUEUE | INFO_FL_CLEAR(v4l2_delete_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..55afbde54211 100644 >>> --- a/include/media/v4l2-ioctl.h >>> +++ b/include/media/v4l2-ioctl.h >>> @@ -163,6 +163,8 @@ struct v4l2_fh; >>>    *    :ref:`VIDIOC_CREATE_BUFS ` ioctl >>>    * @vidioc_prepare_buf: pointer to the function that implements >>>    *    :ref:`VIDIOC_PREPARE_BUF ` ioctl >>> + * @vidioc_delete_bufs: pointer to the function that implements >>> + *    :ref:`VIDIOC_DELETE_BUFS ` ioctl >>>    * @vidioc_overlay: pointer to the function that implements >>>    *    :ref:`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_delete_bufs)(struct file *file, void *fh, >>> +                  struct v4l2_delete_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 97153c69583f..e2c5ff31efd0 100644 >>> --- a/include/media/videobuf2-core.h >>> +++ b/include/media/videobuf2-core.h >>> @@ -843,6 +843,15 @@ 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_delete_buf() - >>> + * @q: pointer to &struct vb2_queue with videobuf2 queue. >>> + * @vb:        pointer to struct &vb2_buffer. >>> + * >>> + *  Return: returns zero on success; an error code otherwise. >>> + */ >>> +int vb2_core_delete_buf(struct vb2_queue *q, struct vb2_buffer *vb); >>> + >>>   /** >>>    * vb2_core_qbuf() - Queue a buffer from userspace >>>    * >>> diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h >>> index 5a845887850b..2ef68fdf388f 100644 >>> --- a/include/media/videobuf2-v4l2.h >>> +++ b/include/media/videobuf2-v4l2.h >>> @@ -118,6 +118,17 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create); >>>    */ >>>   int vb2_prepare_buf(struct vb2_queue *q, struct media_device *mdev, >>>               struct v4l2_buffer *b); >>> +/** >>> + * vb2_delete_bufs() - Delete buffers from the queue >>> + * >>> + * @q:        pointer to &struct vb2_queue with videobuf2 queue. >>> + * @d:        delete parameter, passed from userspace to >>> + *        &v4l2_ioctl_ops->vidioc_delete_bufs handler in driver >>> + * >>> + * The return values from this function are intended to be directly returned >>> + * from &v4l2_ioctl_ops->vidioc_delete_bufs handler in driver. >>> + */ >>> +int vb2_delete_bufs(struct vb2_queue *q, struct v4l2_delete_buffers *d); >> I'm missing the vb2_ioctl_delete_bufs function with a call to vb2_queue_is_busy(). >> >>>     /** >>>    * vb2_qbuf() - Queue a buffer from userspace >>> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h >>> index 78260e5d9985..9cc7f570d995 100644 >>> --- a/include/uapi/linux/videodev2.h >>> +++ b/include/uapi/linux/videodev2.h >>> @@ -2616,6 +2616,20 @@ struct v4l2_create_buffers { >>>       __u32            reserved[6]; >>>   }; >>>   +/** >>> + * struct v4l2_delete_buffers - VIDIOC_DELETE_BUFS argument >>> + * @index:    the first buffer to be deleted >>> + * @count:    number of buffers to delete >>> + * @type:    enum v4l2_buf_type >>> + * @reserved:    future extensions >>> + */ >>> +struct v4l2_delete_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 >>>    * >>> @@ -2715,6 +2729,8 @@ 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_DELETE_BUFS    _IOWR('V', 104, struct v4l2_delete_buffers) >>> + >>>     /* Reminder: when adding new ioctls please add support for them to >>>      drivers/media/v4l2-core/v4l2-compat-ioctl32.c as well! */ >> You need much more extensive compliance checks for this, esp. mixing >> create_bufs and delete_bufs. And test it with the test-media test script. >> >> Regards, >> >>     Hans >> Regards, Hans