From: Hans Verkuil <hverkuil@xs4all.nl>
To: Gustavo Padovan <gustavo@padovan.org>, linux-media@vger.kernel.org
Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
Shuah Khan <shuahkh@osg.samsung.com>,
Pawel Osciak <pawel@osciak.com>,
Alexandre Courbot <acourbot@chromium.org>,
Sakari Ailus <sakari.ailus@iki.fi>,
Brian Starkey <brian.starkey@arm.com>,
Thierry Escande <thierry.escande@collabora.com>,
linux-kernel@vger.kernel.org,
Gustavo Padovan <gustavo.padovan@collabora.com>
Subject: Re: [RFC v5 06/11] [media] vb2: add explicit fence user API
Date: Fri, 17 Nov 2017 14:29:23 +0100 [thread overview]
Message-ID: <6fb67083-7417-0137-9449-36a4cfdb1b9d@xs4all.nl> (raw)
In-Reply-To: <20171115171057.17340-7-gustavo@padovan.org>
On 15/11/17 18:10, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@collabora.com>
>
> Turn the reserved2 field into fence_fd that we will use to send
> an in-fence to the kernel and return an out-fence from the kernel to
> userspace.
>
> Two new flags were added, V4L2_BUF_FLAG_IN_FENCE, that should be used
> when sending a fence to the kernel to be waited on, and
> V4L2_BUF_FLAG_OUT_FENCE, to ask the kernel to give back an out-fence.
>
> v4:
> - make it a union with reserved2 and fence_fd (Hans Verkuil)
>
> v3:
> - make the out_fence refer to the current buffer (Hans Verkuil)
>
> v2: add documentation
>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
> ---
> Documentation/media/uapi/v4l/buffer.rst | 15 +++++++++++++++
> drivers/media/usb/cpia2/cpia2_v4l.c | 2 +-
> drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 4 ++--
> drivers/media/v4l2-core/videobuf2-v4l2.c | 2 +-
> include/uapi/linux/videodev2.h | 7 ++++++-
> 5 files changed, 25 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/media/uapi/v4l/buffer.rst b/Documentation/media/uapi/v4l/buffer.rst
> index ae6ee73f151c..eeefbd2547e7 100644
> --- a/Documentation/media/uapi/v4l/buffer.rst
> +++ b/Documentation/media/uapi/v4l/buffer.rst
> @@ -648,6 +648,21 @@ Buffer Flags
> - Start Of Exposure. The buffer timestamp has been taken when the
> exposure of the frame has begun. This is only valid for the
> ``V4L2_BUF_TYPE_VIDEO_CAPTURE`` buffer type.
> + * .. _`V4L2-BUF-FLAG-IN-FENCE`:
> +
> + - ``V4L2_BUF_FLAG_IN_FENCE``
> + - 0x00200000
> + - Ask V4L2 to wait on fence passed in ``fence_fd`` field. The buffer
> + won't be queued to the driver until the fence signals.
> +
> + * .. _`V4L2-BUF-FLAG-OUT-FENCE`:
> +
> + - ``V4L2_BUF_FLAG_OUT_FENCE``
> + - 0x00400000
> + - Request a fence to be attached to the buffer. The ``fence_fd``
> + field on
> + :ref:`VIDIOC_QBUF` is used as a return argument to send the out-fence
> + fd to userspace.
How would userspace know if fences are not supported? E.g. any driver that does
not use vb2 will have no support for it.
While the driver could clear the flag on return, the problem is that it is a bit
late for applications to discover lack of fence support.
Perhaps we do need a capability flag for this? I wonder what others think.
Regards,
Hans
>
>
>
> diff --git a/drivers/media/usb/cpia2/cpia2_v4l.c b/drivers/media/usb/cpia2/cpia2_v4l.c
> index 3dedd83f0b19..6cde686bf44c 100644
> --- a/drivers/media/usb/cpia2/cpia2_v4l.c
> +++ b/drivers/media/usb/cpia2/cpia2_v4l.c
> @@ -948,7 +948,7 @@ static int cpia2_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
> buf->sequence = cam->buffers[buf->index].seq;
> buf->m.offset = cam->buffers[buf->index].data - cam->frame_buffer;
> buf->length = cam->frame_size;
> - buf->reserved2 = 0;
> + buf->fence_fd = -1;
> buf->reserved = 0;
> memset(&buf->timecode, 0, sizeof(buf->timecode));
>
> diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> index 821f2aa299ae..3a31d318df2a 100644
> --- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> +++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> @@ -370,7 +370,7 @@ struct v4l2_buffer32 {
> __s32 fd;
> } m;
> __u32 length;
> - __u32 reserved2;
> + __s32 fence_fd;
> __u32 reserved;
> };
>
> @@ -533,7 +533,7 @@ static int put_v4l2_buffer32(struct v4l2_buffer *kp, struct v4l2_buffer32 __user
> put_user(kp->timestamp.tv_usec, &up->timestamp.tv_usec) ||
> copy_to_user(&up->timecode, &kp->timecode, sizeof(struct v4l2_timecode)) ||
> put_user(kp->sequence, &up->sequence) ||
> - put_user(kp->reserved2, &up->reserved2) ||
> + put_user(kp->fence_fd, &up->fence_fd) ||
> put_user(kp->reserved, &up->reserved) ||
> put_user(kp->length, &up->length))
> return -EFAULT;
> diff --git a/drivers/media/v4l2-core/videobuf2-v4l2.c b/drivers/media/v4l2-core/videobuf2-v4l2.c
> index 0c0669976bdc..110fb45fef6f 100644
> --- a/drivers/media/v4l2-core/videobuf2-v4l2.c
> +++ b/drivers/media/v4l2-core/videobuf2-v4l2.c
> @@ -203,7 +203,7 @@ static void __fill_v4l2_buffer(struct vb2_buffer *vb, void *pb)
> b->timestamp = ns_to_timeval(vb->timestamp);
> b->timecode = vbuf->timecode;
> b->sequence = vbuf->sequence;
> - b->reserved2 = 0;
> + b->fence_fd = -1;
> b->reserved = 0;
>
> if (q->is_multiplanar) {
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index cd6fc1387f47..311c3a331eda 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -925,7 +925,10 @@ struct v4l2_buffer {
> __s32 fd;
> } m;
> __u32 length;
> - __u32 reserved2;
> + union {
> + __s32 fence_fd;
> + __u32 reserved2;
> + };
> __u32 reserved;
> };
>
> @@ -962,6 +965,8 @@ struct v4l2_buffer {
> #define V4L2_BUF_FLAG_TSTAMP_SRC_SOE 0x00010000
> /* mem2mem encoder/decoder */
> #define V4L2_BUF_FLAG_LAST 0x00100000
> +#define V4L2_BUF_FLAG_IN_FENCE 0x00200000
> +#define V4L2_BUF_FLAG_OUT_FENCE 0x00400000
>
> /**
> * struct v4l2_exportbuffer - export of video buffer as DMABUF file descriptor
>
next prev parent reply other threads:[~2017-11-17 13:29 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-15 17:10 [RFC v5 00/11] V4L2 Explicit Synchronization Gustavo Padovan
2017-11-15 17:10 ` [RFC v5 01/11] [media] v4l: add V4L2_CAP_ORDERED to the uapi Gustavo Padovan
2017-11-17 11:57 ` Mauro Carvalho Chehab
2017-11-17 12:23 ` Gustavo Padovan
2017-11-15 17:10 ` [RFC v5 02/11] [media] vivid: add the V4L2_CAP_ORDERED capability Gustavo Padovan
2017-11-15 17:10 ` [RFC v5 03/11] [media] vb2: add 'ordered_in_driver' property to queues Gustavo Padovan
2017-11-17 5:56 ` Alexandre Courbot
2017-11-17 11:23 ` Gustavo Padovan
2017-11-17 12:15 ` Mauro Carvalho Chehab
2017-11-17 12:27 ` Gustavo Padovan
2017-11-15 17:10 ` [RFC v5 04/11] [media] vivid: mark vivid queues as ordered_in_driver Gustavo Padovan
2017-11-15 17:10 ` [RFC v5 05/11] [media] vb2: check earlier if stream can be started Gustavo Padovan
2017-11-15 17:10 ` [RFC v5 06/11] [media] vb2: add explicit fence user API Gustavo Padovan
2017-11-17 12:25 ` Mauro Carvalho Chehab
2017-11-17 13:29 ` Hans Verkuil [this message]
2017-11-17 13:53 ` Mauro Carvalho Chehab
2017-11-17 14:31 ` Hans Verkuil
2017-11-15 17:10 ` [RFC v5 07/11] [media] vb2: add in-fence support to QBUF Gustavo Padovan
2017-11-17 6:49 ` Alexandre Courbot
2017-11-17 13:00 ` Mauro Carvalho Chehab
2017-11-17 13:08 ` Gustavo Padovan
2017-11-17 13:19 ` Mauro Carvalho Chehab
2017-11-20 11:41 ` Brian Starkey
2017-11-17 13:01 ` Gustavo Padovan
2017-11-20 2:53 ` Alexandre Courbot
2017-11-17 12:53 ` Mauro Carvalho Chehab
2017-11-17 13:12 ` Gustavo Padovan
2017-11-17 13:47 ` Mauro Carvalho Chehab
2017-11-17 17:20 ` Gustavo Padovan
2017-11-17 14:15 ` Hans Verkuil
2017-11-17 17:40 ` Gustavo Padovan
2017-11-17 17:50 ` Gustavo Padovan
2017-11-18 9:30 ` Hans Verkuil
2017-11-15 17:10 ` [RFC v5 08/11] [media] vb2: add videobuf2 dma-buf fence helpers Gustavo Padovan
2017-11-17 7:02 ` Alexandre Courbot
2017-11-17 7:11 ` Alexandre Courbot
2017-11-17 11:27 ` Gustavo Padovan
2017-11-15 17:10 ` [RFC v5 09/11] [media] vb2: add infrastructure to support out-fences Gustavo Padovan
2017-11-17 7:19 ` Alexandre Courbot
2017-11-17 7:29 ` Alexandre Courbot
2017-11-17 11:30 ` Gustavo Padovan
2017-11-15 17:10 ` [RFC v5 10/11] [media] vb2: add out-fence support to QBUF Gustavo Padovan
2017-11-17 7:38 ` Alexandre Courbot
2017-11-17 11:48 ` Gustavo Padovan
2017-11-17 13:34 ` Hans Verkuil
2017-11-15 17:10 ` [RFC v5 11/11] [media] v4l: Document explicit synchronization behavior Gustavo Padovan
2017-11-20 10:19 ` [RFC v5 00/11] V4L2 Explicit Synchronization Smitha T Murthy
2017-11-30 18:53 ` Gustavo Padovan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=6fb67083-7417-0137-9449-36a4cfdb1b9d@xs4all.nl \
--to=hverkuil@xs4all.nl \
--cc=acourbot@chromium.org \
--cc=brian.starkey@arm.com \
--cc=gustavo.padovan@collabora.com \
--cc=gustavo@padovan.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=mchehab@osg.samsung.com \
--cc=pawel@osciak.com \
--cc=sakari.ailus@iki.fi \
--cc=shuahkh@osg.samsung.com \
--cc=thierry.escande@collabora.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).