linux-kernel - Re: [PATCH v5 0/6] driver core: Improve and cleanup driver_deferred_probe_check

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Date:   Tue, 21 Apr 2020 18:16:31 -0700
From:   John Stultz <john.stultz@...aro.org>
To:     Eugeniu Rosca <erosca@...adit-jv.com>
Cc:     lkml <linux-kernel@...r.kernel.org>, Rob Herring <robh@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        Todd Kjos <tkjos@...gle.com>,
        Saravana Kannan <saravanak@...gle.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Thierry Reding <treding@...dia.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        linux-renesas-soc@...r.kernel.org,
        Eugeniu Rosca <roscaeugeniu@...il.com>
Subject: Re: [PATCH v5 0/6] driver core: Improve and cleanup driver_deferred_probe_check_state()

On Tue, Apr 21, 2020 at 4:59 PM Eugeniu Rosca <erosca@...adit-jv.com> wrote:
>
> Hi John,
> Cc: linux-renesas-soc
>
> On Tue, Feb 25, 2020 at 05:08:22AM +0000, John Stultz wrote:
> > This series goal is to improve and cleanup the
> > driver_deferred_probe_check_state() code in the driver core.
> >
> > This series is useful for being able to support modules
> > dependencies which may be loaded by userland, far after
> > late_initcall is done. For instance, this series allows us to
> > successfully use various clk drivers as modules on the db845c
> > board. And without it, those drivers have to be statically built
> > in to work.
> >
> > Since I first sent out this patch, Saravana suggested an
> > alternative approach which also works for our needs, and is a
> > bit simpler:
> >  https://lore.kernel.org/lkml/20200220055250.196456-1-saravanak@google.com/T/#u
> >
> > However, while that patch provides the functionality we need,
> > I still suspect the driver_deferred_probe_check_state() code
> > could benefit from the cleanup in this patch, as the existing
> > logic is somewhat muddy.
> >
> > New in v5:
> > * Reworked the driver_deferred_probe_check_state() logic as
> >   suggested by Saravana to tie the initcall_done checking with
> >   modules being enabled.
> > * Cleanup some comment wording as suggested by Rafael
> > * Try to slightly simplify the regulator logic as suggested by
> >   Bjorn
> >
> > Thanks so much to Bjorn, Saravana and Rafael for their reviews
> > and suggestions! Additional review and feedback is always greatly
> > appreciated!
>
> Building a recent [0] kernel using vanilla arm64 defconfig
> and booting it on H3ULCB, I get buried into backtraces [1].
>
> After reverting this series, up to and including its first commit,
> booting goes back to normal [2].
>
> Any chance to get a fix or at least some hints where to dig into?

Yea. There's two patch sets I have for this. The first quiets down the
warnings(we don't need stack dumps for these):
  https://lore.kernel.org/lkml/20200330202715.86609-1-john.stultz@linaro.org/

The second reverts the default timeout back to 0:
  https://lore.kernel.org/lkml/20200413204253.84991-1-john.stultz@linaro.org/


Let me know if those work for you, or if you're still having trouble
afterwards.  I need to resubmit the set as I'm guessing they've been
overlooked.

thanks
-john