linux-kernel - Re: [PATCH v2 12/29] venus: add common capability parser

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Message-ID: <CAAFQd5CR8fOjKkhkyGhFNk-E-fj5pHjT9jT42+MXd8PmAk-i9g@mail.gmail.com>
Date:   Thu, 5 Jul 2018 19:14:18 +0900
From:   Tomasz Figa <tfiga@...omium.org>
To:     Stanimir Varbanov <stanimir.varbanov@...aro.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...all.nl>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        vgarodia@...eaurora.org
Subject: Re: [PATCH v2 12/29] venus: add common capability parser

On Thu, Jul 5, 2018 at 6:45 PM Stanimir Varbanov
<stanimir.varbanov@...aro.org> wrote:
>
> Hi Tomasz,
>
> On 07/02/2018 01:05 PM, Tomasz Figa wrote:
> > On Mon, Jul 2, 2018 at 6:59 PM Stanimir Varbanov
> > <stanimir.varbanov@...aro.org> wrote:
> >>
> >> Hi Tomasz,
> >>
> >> On 07/02/2018 12:23 PM, Tomasz Figa wrote:
> >>> On Thu, May 31, 2018 at 4:06 PM Tomasz Figa <tfiga@...omium.org> wrote:
> >>>>
> >>>> On Thu, May 31, 2018 at 1:21 AM Stanimir Varbanov
> >>>> <stanimir.varbanov@...aro.org> wrote:
> >>>>>
> >>>>> Hi Tomasz,
> >>>>>
> >>>>> On 05/24/2018 05:16 PM, Tomasz Figa wrote:
> >>>>>> Hi Stanimir,
> >>>>>>
> >>>>>> On Tue, May 15, 2018 at 5:08 PM Stanimir Varbanov <
> >>> [snip]
> >>>>>>
> >>>>>>> +                       break;
> >>>>>>> +               }
> >>>>>>> +
> >>>>>>> +               word++;
> >>>>>>> +               words_count--;
> >>>>>>
> >>>>>> If data is at |word + 1|, shouldn’t we increment |word| by |1 + |data
> >>>>>> size||?
> >>>>>
> >>>>> yes, that could be possible but the firmware packets are with variable
> >>>>> data length and don't want to make the code so complex.
> >>>>>
> >>>>> The idea is to search for HFI_PROPERTY_PARAM* key numbers. Yes it is not
> >>>>> optimal but this enumeration is happen only once during driver probe.
> >>>>>
> >>>>
> >>>> Hmm, do we have a guarantee that we will never find a value that
> >>>> matches HFI_PROPERTY_PARAM*, but would be actually just some data
> >>>> inside the payload?
> >>>
> >>> Ping?
> >>
> >> OK, you are right there is guarantee that we not mixing keywords and
> >
> > Did the auto-correction engine in my head got this correctly as "no
> > guarantee"? :)
> >
> >> data. I can make parse_* functions to return how words they consumed and
> >> increment 'word' pointer with consumed words.
> >
> > Yes, that or maybe just returning the pointer to the first word after
> > consumed data. Most of the looping functions already seem to have this
> > value, so it would have to be just returned. (vs having to subtract
> > from the start pointer)
>
> I made the relevant changes to satisfy you request but the results were
> fine for Venus v3 and wrong on v1. So I'd propose to postpone this
> change and fix it with follow up patches because I don't want miss the
> next merge window. So far the supported venus firmware versions are fine
> with the current parser implementation.
>
> What you think?

Fair enough. Generally with the design of those metadata, fixing this
problem seems to be quite non-trivial. Let's keep it as is for now.

Best regards,
Tomasz