linux-kernel - Re: [PATCH] pinctrl: devicetree: Keep deferring even on timeout

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Date:   Fri, 28 Aug 2020 14:42:26 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        John Stultz <john.stultz@...aro.org>
Subject: Re: [PATCH] pinctrl: devicetree: Keep deferring even on timeout

On Tue, Aug 25, 2020 at 4:33 PM Thierry Reding <thierry.reding@...il.com> wrote:

> From: Thierry Reding <treding@...dia.com>
>
> driver_deferred_probe_check_state() may return -ETIMEDOUT instead of
> -EPROBE_DEFER after all built-in drivers have been probed. This can
> cause issues for built-in drivers that depend on resources provided by
> loadable modules.
>
> One such case happens on Tegra where I2C controllers are used during
> early boot to set up the system PMIC, so the I2C driver needs to be a
> built-in driver. At the same time, some instances of the I2C controller
> depend on the DPAUX hardware for pinmuxing. Since the DPAUX is handled
> by the display driver, which is usually not built-in, the pin control
> states will not become available until after the root filesystem has
> been mounted and the display driver loaded from it.
>
> Fixes: bec6c0ecb243 ("pinctrl: Remove use of driver_deferred_probe_check_state_continue()")
> Suggested-by: John Stultz <john.stultz@...aro.org>
> Signed-off-by: Thierry Reding <treding@...dia.com>

Just like with the identical patch from John I got a while back, I'd like
some nod from the device core maintainers (Greg or Raphael) that this
is how we want to do things.

Yours,
Linus Walleij