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Alexandre Courbot Cc: Cornelia Huck , virtio-dev@lists.oasis-open.org, Keiichi Watanabe , =?UTF-8?Q?Alex_Benn=c3=a9e?= , Marcin Wojtas , =?UTF-8?Q?Matti_M=c3=b6ll?= , Andrew Gazizov , Enrico Granata , Gustavo Padovan , Peter Griffin , Tomasz Figa , Daniel Almeida , Enric Balletbo i Serra , Albert Esteve , bgrzesik@google.com, "srosek@google.com" , "zyta@google.com" , hmazur@google.com, mikrawczyk@google.com References: <20221208072325.2259940-1-acourbot@chromium.org> <8ec36252-97c6-0378-e25b-fc972ea3a66d@opensynergy.com> <909867c6-b66c-1281-45a7-38fd0aa32123@opensynergy.com> <87cz6mnaqk.fsf@redhat.com> <877cwttw2x.fsf@redhat.com> <87a60kg9rh.fsf@redhat.com> <877cvog030.fsf@redhat.com> <87o7nmk1rs.fsf@redhat.com> <96978ce8-0837-2e08-f5ca-66587807798b@opensynergy.com> From: Alexander Gordeev In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: BE1P281CA0382.DEUP281.PROD.OUTLOOK.COM (2603:10a6:b10:80::12) To 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UltUe96Q3vHA7aESDIF73yj6fMTph1hZnBct6gxmHpruxVd2C454PINaTEE bxexq/MBnRGI3zy4+u43lnn6FcEyJPi3QPpZp9xYsc4H4wucQPnRnV2pSXr9yJY5w4V/SPoR7lf 6mg4k8lSCy3xZ1iF92Xi9xtDYmWNNAVmdkuKA5vlZf5clFtzkRsEyEJc3/UCakE8ikcnnWUM9Pg 0xieNAZQkYjOH+EaBr96bQTSKyVGLaxO5JIB2OeVwjut4bKXPb7Ejn5CpPDXJmUyH/S/Lthx+nI jvCfFVqcEYjnTJQ=.I4aCV4I2EXqf/8JF8od+SSKyzQ2FykhY6h6atU7rhrYyR4Nv9l3H8sSIBV uGeNp0qBbbGOmOeN1VB6S8OBBbegExwlIZ+5zItYSxcodVRgbnCJC43DPM5B8OE2VgeSrI61p6Q YJCX/kwQp2fbplxeOnQ4NXwGDmLOVrp/rLviRjL5fWnhtpSCQYVLt+ALTEoWX/l9pHa8g+eXSHV LHJHNiQf3Hl/XPqilmZNLAms56cpLjtCvfzbO8anlpWdIQI+f7mDKIzab7aGT+ARNc3VyKh205D bGgqLDamnMkAm9L+TkR3Dr8W/HQxSCXlwMtUflszEhZPmMDcjueUmNy6fDw== X-TM-Addin-ProductCode: EMS Subject: Re: [virtio-dev] Re: [RFC PATCH v6] virtio-video: Add virtio video device specification Hi Bart=C5=82omiej, On 21.04.23 13:49, Bart=C5=82omiej Grzesik wrote: > +CC chromeos-arc-video-eng team that also works on virtio-video > > Hi everyone! > > From the experience of working on virtio-video I can definitely agree > with Alex Courbot, that moving to virtio-v4l2 will be a great move. > This move will not only simply things a lot but also allow us things like > vhost-net like implementation for some devices (however this is > thinking way ahead and linux only). > > One added benefit of this move that I'd like to point out now, that > probably > haven't been mentioned before, is moving to asynchronous resource queue > call. Previously `VIRTIO_VIDEO_CMD_RESOURCE_QUEUE` have been > synchronous and caused one hard to debug bug caused by this flawed > design. During the command execution the virtio queue descriptors are > blocked, potentially leading to dead locking the device. The implementati= on > of virtio-v4l2 (even as is - btw nice work Alex!) eliminates this issue > by moving to asynchronous response of the resource queue (VIDIOC_QBUF). Thanks for your valuable feedback! Could you please share some details about the bug? That would be very helpful. I'm working on the next version of the virtio-video draft, so I can change it there. I like the idea to use V4L2 as a reference, so we should probably do it like it is done there, only simpler. Still it would be interesting to know the details, because we didn't have issues with the current design. > I also agree that in this case v4l2 would only be a protocol similar to h= ow > virtio-video was, that has the benefit of allowing very simple guest > drivers. -- Alexander Gordeev Senior Software Engineer OpenSynergy GmbH Rotherstr. 20, 10245 Berlin Phone: +49 30 60 98 54 0 - 88 Fax: +49 (30) 60 98 54 0 - 99 EMail: alexander.gordeev@opensynergy.com www.opensynergy.com Handelsregister/Commercial Registry: Amtsgericht Charlottenburg, HRB 108616= B Gesch=C3=A4ftsf=C3=BChrer/Managing Director: R=C3=A9gis Adjamah Please mind our privacy notice pursuant to Art. 13 GDPR. // Unsere= Hinweise zum Datenschutz gem. Art. 13 DSGVO finden Sie hier. --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org