linux-kernel - Re: [tip: timers/core] clocksource/drivers/timer-probe: Avoid creating dead devices

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Message-ID: <CAGETcx_BZhSmUpN+Gssp1jcjGzG7SdOmg9TAQRhn4q4G_rFUfg@mail.gmail.com>
Date:   Wed, 25 Mar 2020 16:06:15 -0700
From:   Saravana Kannan <saravanak@...gle.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Ionela Voinescu <ionela.voinescu@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        linux-tip-commits@...r.kernel.org, x86 <x86@...nel.org>,
        liviu.dudau@....com, sudeep.holla@....com,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jon Hunter <jonathanh@...dia.com>
Subject: Re: [tip: timers/core] clocksource/drivers/timer-probe: Avoid
 creating dead devices

On Wed, Mar 25, 2020 at 3:56 PM Saravana Kannan <saravanak@...gle.com> wrote:
>
> On Wed, Mar 25, 2020 at 2:47 PM Thomas Gleixner <tglx@...utronix.de> wrote:
> >
> > Saravana Kannan <saravanak@...gle.com> writes:
> > > On Tue, Mar 24, 2020 at 11:34 AM Saravana Kannan <saravanak@...gle.com> wrote:
> > > I took a closer look. So two different drivers [1] [2] are saying they
> > > know how to handle "arm,vexpress-sysreg" and are expecting to run at
> > > the same time. That seems a bit unusual to me. I wonder if this is a
> > > violation of the device-driver model because this expectation would
> > > never be allowed if these device drivers were actual drivers
> > > registered with driver-core. But that's a discussion for another time.
> > >
> > > To fix this issue you are facing, this patch should work:
> > > https://lore.kernel.org/lkml/20200324195302.203115-1-saravanak@google.com/T/#u
> >
> > Sorry, that's not a fix. That's a crude hack.
>
> If device nodes are being handled by drivers without binding a driver
> to struct devices, then not setting OF_POPULATED is wrong. So the
> original patch sets it. There are also very valid reasons for allowing
> OF_POPULATED to be cleared by a driver as discussed here [1].

Forgot to include [1]
[1] - https://lore.kernel.org/lkml/20200111052125.238212-1-saravanak@google.com/T/#m7b043de4c75e6c1de309d3ca5146bb0c7b3dfc80
For some reason Paul's email is missing from lore.kernel.org.

-Saravana