linux-kernel - Re: [PATCH v2] driver core: Extend returning EPROBE_DEFER for two minutes after late

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Date:   Fri, 14 Feb 2020 15:34:11 -0800
From:   John Stultz <john.stultz@...aro.org>
To:     lkml <linux-kernel@...r.kernel.org>
Cc:     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>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v2] driver core: Extend returning EPROBE_DEFER for two
 minutes after late_initcall

On Fri, Feb 14, 2020 at 3:32 PM John Stultz <john.stultz@...aro.org> wrote:
>
> Due to commit e01afc3250255 ("PM / Domains: Stop deferring probe
> at the end of initcall"), along with commit 25b4e70dcce9
> ("driver core: allow stopping deferred probe after init") after
> late_initcall, drivers will stop getting EPROBE_DEFER, and
> instead see an error causing the driver to fail to load.
>
> That change causes trouble when trying to use many clk drivers
> as modules, as the clk modules may not load until much later
> after init has started. If a dependent driver loads and gets an
> error instead of EPROBE_DEFER, it won't try to reload later when
> the dependency is met, and will thus fail to load.
>
> Instead of reverting that patch, this patch tries to extend the
> time that EPROBE_DEFER is retruned by 30 seconds, to (hopefully)
> ensure that everything has had a chance to load.

Oh, and of course I forgot to fix the subject line and didn't see it
until git send-email was done.  That should be 30 seconds, not two
minutes. I'll fix that up for the next version.

Apologies!
-john