linux-kernel - Re: [PATCH 00/10] Venus stateful Codec API

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Date:   Mon, 28 Jan 2019 13:30:32 +0900
From:   Tomasz Figa <tfiga@...omium.org>
To:     Alexandre Courbot <acourbot@...omium.org>
Cc:     Stanimir Varbanov <stanimir.varbanov@...aro.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...all.nl>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Vikash Garodia <vgarodia@...eaurora.org>,
        Malathi Gottam <mgottam@...eaurora.org>
Subject: Re: [PATCH 00/10] Venus stateful Codec API

On Mon, Jan 28, 2019 at 1:16 PM Alexandre Courbot <acourbot@...omium.org> wrote:
>
> On Fri, Jan 25, 2019 at 7:35 PM Stanimir Varbanov
> <stanimir.varbanov@...aro.org> wrote:
> >
> > Hi Alex,
> >
> > On 1/25/19 7:34 AM, Alexandre Courbot wrote:
> > > On Thu, Jan 24, 2019 at 7:13 PM Stanimir Varbanov
> > > <stanimir.varbanov@...aro.org> wrote:
> > >>
> > >> Hi Alex,
> > >>
> > >> Thank you for review and valuable comments!
> > >>
> > >> On 1/24/19 10:43 AM, Alexandre Courbot wrote:
> > >>> Hi Stanimir,
> > >>>
> > >>> On Fri, Jan 18, 2019 at 1:20 AM Stanimir Varbanov
> > >>> <stanimir.varbanov@...aro.org> wrote:
> > >>>>
> > >>>> Hello,
> > >>>>
> > >>>> This aims to make Venus decoder compliant with stateful Codec API [1].
> > >>>> The patches 1-9 are preparation for the cherry on the cake patch 10
> > >>>> which implements the decoder state machine similar to the one in the
> > >>>> stateful codec API documentation.
> > >>>
> > >>> Thanks *a lot* for this series! I am still stress-testing it against
> > >>> the Chromium decoder tests, but so far it has been rock-solid. I have
> > >>> a few inline comments on some patches ; I will also want to review the
> > >>> state machine more thoroughly after refreshing my mind on Tomasz doc,
> > >>> but this looks pretty promising already.
> > >>
> > >> I'm expecting problems with ResetAfterFirstConfigInfo. I don't know why
> > >> but this test case is very dirty. I'd appreciate any help to decipher
> > >> what is the sequence of v4l2 calls made by this unittest case.
> > >
> > > I did not see any issue with ResetAfterFirstConfigInfo, however
> > > ResourceExhaustion seems to hang once in a while. But I could already
> > > see this behavior with the older patchset.
> >
> > Is it hangs badly?
>
> It just stops processing, no crash. I need to investigate more closely.
>
> > >
> > > In any case I plan to thoroughly review the state machine. I agree it
> > > is a bit complex to grasp.
> >
> > yes the state machine isn't simple and I blamed Tomasz many times for
> > that :)

Don't shoot the messenger! I'm just carrying what hardware and
userspace made for us. ;)

>
> If I feel inspired I may try to extract the useful part of your patch
> into a framework that we can use everywhere. :) We don't want every
> driver to reimplement this complex state machine and introduce new
> bugs every time.

Yeah, we definitely need such a framework, especially given how the
m2m framework is overused for handling codecs.

Best regards,
Tomasz