From: Dmitry Sepp <dmitry.sepp@opensynergy.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: Keiichi Watanabe <keiichiw@chromium.org>,
<virtio-dev@lists.oasis-open.org>, <linux-media@vger.kernel.org>,
<acourbot@chromium.org>, <alexlau@chromium.org>,
<daniel@ffwll.ch>, <dgreid@chromium.org>, <egranata@google.com>,
<fziglio@redhat.com>, <hverkuil@xs4all.nl>,
<marcheu@chromium.org>, <posciak@chromium.org>,
<spice-devel@lists.freedesktop.org>, <stevensd@chromium.org>,
<tfiga@chromium.org>, <uril@redhat.com>
Subject: Re: [PATCH v2 1/1] virtio-video: Add virtio video device specification
Date: Thu, 19 Dec 2019 10:26:37 +0100 [thread overview]
Message-ID: <2570078.xtWa8k4VtA@os-lin-dmo> (raw)
In-Reply-To: <20191218134037.3jbouht52bxqwfyy@sirius.home.kraxel.org>
Hi Gerd,
On Mittwoch, 18. Dezember 2019 14:40:37 CET Gerd Hoffmann wrote:
> Hi,
>
> > +The device MUST mark the last buffer with the
> > +VIRTIO_VIDEO_BUFFER_F_EOS flag to denote completion of the drain
> > +sequence.
>
> No, that would build a race condition into the protocol. The device
> could complete the last buffer after the driver has sent the drain
> command but before the device saw it. So the flag would not be
> reliable.
No, then it means the device was not in drain, but, for example, hit a
resolution change in the stream and tells us that this is the last buffer with
the old resolution.
>
> I also can't see why the flag is needed in the first place. The driver
> should know which buffers are queued still and be able to figure
> whenever the drain is complete or not without depending on that flag.
> So I'd suggest to simply drop it.
This flag is used not for drain only. In marks the completion of whatever
specific buffer sequence, like a full end-of-stream, resolution change, drain
etc. We also need this to handle nested sequences. For instance, a resolution
change event might happen while in drain.
Regards,
Dmitry.
>
> That is the only issue I've spotted in the protocol on a first quick
> look. There are a few places where the spec text could be improved.
> I'll try to set aside some time to go over this in detail, but I can't
> promise I'll find the time to do that before xmas and new year.
>
> cheers,
> Gerd
WARNING: multiple messages have this Message-ID (diff)
From: Dmitry Sepp <dmitry.sepp@opensynergy.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: Keiichi Watanabe <keiichiw@chromium.org>,
virtio-dev@lists.oasis-open.org, linux-media@vger.kernel.org,
acourbot@chromium.org, alexlau@chromium.org, daniel@ffwll.ch,
dgreid@chromium.org, egranata@google.com, fziglio@redhat.com,
hverkuil@xs4all.nl, marcheu@chromium.org, posciak@chromium.org,
spice-devel@lists.freedesktop.org, stevensd@chromium.org,
tfiga@chromium.org, uril@redhat.com
Subject: [virtio-dev] Re: [PATCH v2 1/1] virtio-video: Add virtio video device specification
Date: Thu, 19 Dec 2019 10:26:37 +0100 [thread overview]
Message-ID: <2570078.xtWa8k4VtA@os-lin-dmo> (raw)
In-Reply-To: <20191218134037.3jbouht52bxqwfyy@sirius.home.kraxel.org>
Hi Gerd,
On Mittwoch, 18. Dezember 2019 14:40:37 CET Gerd Hoffmann wrote:
> Hi,
>
> > +The device MUST mark the last buffer with the
> > +VIRTIO_VIDEO_BUFFER_F_EOS flag to denote completion of the drain
> > +sequence.
>
> No, that would build a race condition into the protocol. The device
> could complete the last buffer after the driver has sent the drain
> command but before the device saw it. So the flag would not be
> reliable.
No, then it means the device was not in drain, but, for example, hit a
resolution change in the stream and tells us that this is the last buffer with
the old resolution.
>
> I also can't see why the flag is needed in the first place. The driver
> should know which buffers are queued still and be able to figure
> whenever the drain is complete or not without depending on that flag.
> So I'd suggest to simply drop it.
This flag is used not for drain only. In marks the completion of whatever
specific buffer sequence, like a full end-of-stream, resolution change, drain
etc. We also need this to handle nested sequences. For instance, a resolution
change event might happen while in drain.
Regards,
Dmitry.
>
> That is the only issue I've spotted in the protocol on a first quick
> look. There are a few places where the spec text could be improved.
> I'll try to set aside some time to go over this in detail, but I can't
> promise I'll find the time to do that before xmas and new year.
>
> cheers,
> Gerd
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next prev parent reply other threads:[~2019-12-19 9:26 UTC|newest]
Thread overview: 147+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 13:02 [PATCH v2 0/1] VirtIO video device specification Keiichi Watanabe
2019-12-18 13:02 ` [virtio-dev] " Keiichi Watanabe
2019-12-18 13:02 ` [PATCH v2 1/1] virtio-video: Add virtio " Keiichi Watanabe
2019-12-18 13:02 ` [virtio-dev] " Keiichi Watanabe
2019-12-18 13:40 ` Gerd Hoffmann
2019-12-18 13:40 ` [virtio-dev] " Gerd Hoffmann
2019-12-18 14:08 ` Tomasz Figa
2019-12-18 14:08 ` Tomasz Figa
2019-12-19 7:46 ` Gerd Hoffmann
2019-12-19 7:46 ` Gerd Hoffmann
2019-12-19 9:48 ` Dmitry Sepp
2019-12-19 9:48 ` Dmitry Sepp
2019-12-19 9:59 ` Tomasz Figa
2019-12-19 9:59 ` Tomasz Figa
2019-12-19 10:54 ` Dmitry Sepp
2019-12-19 10:54 ` Dmitry Sepp
2019-12-19 12:05 ` Tomasz Figa
2019-12-19 12:05 ` Tomasz Figa
2019-12-19 13:12 ` Gerd Hoffmann
2019-12-19 13:12 ` Gerd Hoffmann
2020-01-08 13:52 ` Keiichi Watanabe
2020-01-08 13:52 ` Keiichi Watanabe
2020-01-09 13:40 ` Gerd Hoffmann
2020-01-09 13:40 ` Gerd Hoffmann
2020-01-09 14:20 ` Tomasz Figa
2020-01-09 14:20 ` Tomasz Figa
2020-01-14 7:18 ` Keiichi Watanabe
2020-01-14 7:18 ` Keiichi Watanabe
2020-01-14 10:35 ` Dmitry Sepp
2020-01-14 10:35 ` Dmitry Sepp
2020-01-15 7:49 ` Keiichi Watanabe
2020-01-15 7:49 ` Keiichi Watanabe
2020-01-15 11:12 ` Tomasz Figa
2020-01-15 11:12 ` Tomasz Figa
2019-12-19 13:01 ` Gerd Hoffmann
2019-12-19 13:01 ` Gerd Hoffmann
2020-01-08 13:50 ` Keiichi Watanabe
2020-01-08 13:50 ` Keiichi Watanabe
2019-12-19 9:26 ` Dmitry Sepp [this message]
2019-12-19 9:26 ` Dmitry Sepp
2019-12-19 9:59 ` Tomasz Figa
2019-12-19 9:59 ` [virtio-dev] " Tomasz Figa
2019-12-19 12:54 ` Gerd Hoffmann
2019-12-19 12:54 ` [virtio-dev] " Gerd Hoffmann
2019-12-18 17:29 ` Frediano Ziglio
2019-12-20 14:05 ` Keiichi Watanabe
2019-12-20 14:05 ` [virtio-dev] " Keiichi Watanabe
2019-12-20 15:33 ` Dmitry Sepp
2019-12-20 15:33 ` [virtio-dev] " Dmitry Sepp
2019-12-19 13:28 ` Dmitry Sepp
2019-12-19 13:28 ` [virtio-dev] " Dmitry Sepp
2019-12-20 15:26 ` Keiichi Watanabe
2019-12-20 15:26 ` [virtio-dev] " Keiichi Watanabe
2019-12-20 15:46 ` Dmitry Sepp
2019-12-21 6:46 ` Tomasz Figa
2019-12-21 6:46 ` [virtio-dev] " Tomasz Figa
2019-12-30 12:16 ` Dmitry Sepp
2019-12-30 12:16 ` Dmitry Sepp
2020-01-06 6:31 ` Tomasz Figa
2020-01-06 6:31 ` Tomasz Figa
2020-01-06 8:33 ` Gerd Hoffmann
2020-01-06 8:33 ` Gerd Hoffmann
2020-01-06 9:29 ` Dmitry Sepp
2020-01-06 9:29 ` Dmitry Sepp
2020-01-03 15:47 ` Dmitry Sepp
2020-01-03 15:47 ` [virtio-dev] " Dmitry Sepp
2020-01-06 8:47 ` Gerd Hoffmann
2020-01-06 8:47 ` [virtio-dev] " Gerd Hoffmann
2020-01-06 10:21 ` Keiichi Watanabe
2020-01-06 10:21 ` [virtio-dev] " Keiichi Watanabe
2020-01-06 14:59 ` Dmitry Sepp
2020-01-06 14:59 ` [virtio-dev] " Dmitry Sepp
2020-01-07 13:24 ` Keiichi Watanabe
2020-01-07 13:24 ` [virtio-dev] " Keiichi Watanabe
2020-01-07 16:50 ` Dmitry Sepp
2020-01-07 16:50 ` [virtio-dev] " Dmitry Sepp
2020-01-08 6:59 ` Keiichi Watanabe
2020-01-08 6:59 ` [virtio-dev] " Keiichi Watanabe
2020-01-08 10:00 ` Dmitry Sepp
2020-01-08 10:00 ` [virtio-dev] " Dmitry Sepp
2020-01-08 12:14 ` Keiichi Watanabe
2020-01-08 12:14 ` [virtio-dev] " Keiichi Watanabe
2020-01-08 12:46 ` Tomasz Figa
2020-01-08 12:46 ` [virtio-dev] " Tomasz Figa
2020-01-08 13:05 ` Keiichi Watanabe
2020-01-08 13:05 ` [virtio-dev] " Keiichi Watanabe
2020-01-08 13:11 ` Dmitry Sepp
2020-01-08 13:11 ` [virtio-dev] " Dmitry Sepp
2020-01-08 13:23 ` Keiichi Watanabe
2020-01-08 13:23 ` Keiichi Watanabe
2020-01-08 12:23 ` Keiichi Watanabe
2020-01-08 12:23 ` [virtio-dev] " Keiichi Watanabe
2019-12-20 15:58 ` [PATCH v2 0/1] VirtIO " Dmitry Sepp
2019-12-20 15:58 ` [virtio-dev] " Dmitry Sepp
2019-12-21 4:36 ` Keiichi Watanabe
2019-12-21 4:36 ` [virtio-dev] " Keiichi Watanabe
2019-12-21 6:18 ` Tomasz Figa
2019-12-21 6:18 ` [virtio-dev] " Tomasz Figa
2019-12-21 6:19 ` Tomasz Figa
2019-12-21 6:19 ` [virtio-dev] " Tomasz Figa
2020-01-03 13:05 ` Dmitry Sepp
2020-01-03 13:05 ` [virtio-dev] " Dmitry Sepp
2020-01-06 10:30 ` Keiichi Watanabe
2020-01-06 10:30 ` [virtio-dev] " Keiichi Watanabe
2020-01-06 11:28 ` Dmitry Sepp
2020-01-06 11:28 ` [virtio-dev] " Dmitry Sepp
2020-01-07 10:25 ` Keiichi Watanabe
2020-01-07 10:25 ` [virtio-dev] " Keiichi Watanabe
2020-01-09 14:56 ` Dmitry Sepp
2020-01-09 14:56 ` [virtio-dev] " Dmitry Sepp
2020-01-10 10:16 ` Dmitry Sepp
2020-01-10 10:16 ` Dmitry Sepp
2020-01-10 13:53 ` Keiichi Watanabe
2020-01-10 13:53 ` Keiichi Watanabe
2020-01-10 15:11 ` Dmitry Sepp
2020-01-10 15:11 ` Dmitry Sepp
2020-01-11 16:06 ` Tomasz Figa
2020-01-11 16:06 ` Tomasz Figa
2020-01-13 9:50 ` Dmitry Sepp
2020-01-13 9:50 ` Dmitry Sepp
2020-01-15 11:23 ` Keiichi Watanabe
2020-01-15 11:23 ` Keiichi Watanabe
2020-01-13 9:56 ` Gerd Hoffmann
2020-01-13 9:56 ` Gerd Hoffmann
2020-01-13 10:41 ` Dmitry Sepp
2020-01-13 11:05 ` Gerd Hoffmann
2020-01-13 11:05 ` Gerd Hoffmann
2020-01-13 11:59 ` Tomasz Figa
2020-01-13 11:59 ` Tomasz Figa
2020-01-13 13:26 ` Gerd Hoffmann
2020-01-13 13:26 ` Gerd Hoffmann
2020-01-15 11:00 ` Tomasz Figa
2020-01-15 11:00 ` Tomasz Figa
2020-01-15 11:23 ` Keiichi Watanabe
2020-01-15 11:23 ` Keiichi Watanabe
2020-01-15 11:26 ` Gerd Hoffmann
2020-01-15 11:26 ` Gerd Hoffmann
2020-01-20 7:20 ` Keiichi Watanabe
2020-01-20 7:20 ` Keiichi Watanabe
2020-01-20 10:47 ` Gerd Hoffmann
2020-01-20 10:47 ` Gerd Hoffmann
2020-01-21 2:47 ` Keiichi Watanabe
2020-01-21 2:47 ` Keiichi Watanabe
2020-01-21 6:44 ` Gerd Hoffmann
2020-01-21 6:44 ` Gerd Hoffmann
2020-01-21 8:56 ` Keiichi Watanabe
2020-01-21 8:56 ` Keiichi Watanabe
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