linux-kernel - Re: [PATCH v2] media: venus: Synchronize probe() between venus

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Message-ID: <CALAqxLWjK4h-ghF5s8qV6Q3Wp3K1N816dTfiLNatBTms6NDe3A@mail.gmail.com>
Date:   Wed, 8 Dec 2021 19:11:13 -0800
From:   John Stultz <john.stultz@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Stanimir Varbanov <stanimir.varbanov@...aro.org>
Cc:     Tadeusz Struk <tadeusz.struk@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Amit Pundir <amit.pundir@...aro.org>,
        linux-media@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] media: venus: Synchronize probe() between venus_core
 and enc/dec

On Tue, Nov 30, 2021 at 8:49 PM John Stultz <john.stultz@...aro.org> wrote:
> On Tue, Nov 23, 2021 at 7:29 PM Bjorn Andersson
> <bjorn.andersson@...aro.org> wrote:
> > Rather than trying to synchronize away the side effects of
> > of_platform_populate() I think we should stop using it.
> >
> > I had the very same problem in the qcom_wcnss remoteproc driver and
> > in below change I got rid of that by manually initializing a struct
> > device for the child node. In the event that the child probe defer I
> > would just probe defer the parent as well.
> >
> > 1fcef985c8bd ("remoteproc: qcom: wcnss: Fix race with iris probe")
> >
> > The change might look a little bit messy, but the end result it much
> > cleaner than relying on various locks etc.
> >
> >
> > But in the qcom_wcnss case I have a child _device_ because I need
> > something to do e.g. regulator_get() on. I fail to see why venc and vdec
> > are devices in the first place.
>
> I definitely agree with Bjorn that all this asynchronous component
> probing feels overly complicated, and a rework is probably the better
> solution.
>
> Though my only question is:  is someone planning to do this rework?
>
> In the meantime, Tadeusz' patch does resolve a *very* frequent boot
> crash seen when the venus driver is enabled.
> So Stanimir, should we consider merging this as a stop gap until the
> larger probe rework is done?

Stanimir? Does the above sound reasonable?

thanks
-john