linux-kernel - Re: [RFC PATCH v1 2/9] pinctrl: devicetree: Delete usage of driver_deferred_probe_check

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Date:   Mon, 6 Jun 2022 13:17:24 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>,
        Mark Brown <broonie@...nel.org>, Rob Herring <robh@...nel.org>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        John Stultz <jstultz@...gle.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Android Kernel Team <kernel-team@...roid.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
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        ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: Re: [RFC PATCH v1 2/9] pinctrl: devicetree: Delete usage of
 driver_deferred_probe_check_state()

On Sat, Jun 04, 2022 at 08:41:01PM -0700, Saravana Kannan wrote:
> On Mon, May 30, 2022 at 2:22 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > On Thu, May 26, 2022 at 10:16 AM Saravana Kannan <saravanak@...gle.com> wrote:
> > > Now that fw_devlink=on by default and fw_devlink supports
> > > "pinctrl-[0-8]" property, the execution will never get to the point
> >
> > 0-9?
> >
> > oh, it's really 0-8:
> >
> >     drivers/of/property.c:DEFINE_SIMPLE_PROP(pinctrl0, "pinctrl-0", NULL)
> >     drivers/of/property.c:DEFINE_SIMPLE_PROP(pinctrl1, "pinctrl-1", NULL)
> >     drivers/of/property.c:DEFINE_SIMPLE_PROP(pinctrl2, "pinctrl-2", NULL)
> >     drivers/of/property.c:DEFINE_SIMPLE_PROP(pinctrl3, "pinctrl-3", NULL)
> >     drivers/of/property.c:DEFINE_SIMPLE_PROP(pinctrl4, "pinctrl-4", NULL)
> >     drivers/of/property.c:DEFINE_SIMPLE_PROP(pinctrl5, "pinctrl-5", NULL)
> >     drivers/of/property.c:DEFINE_SIMPLE_PROP(pinctrl6, "pinctrl-6", NULL)
> >     drivers/of/property.c:DEFINE_SIMPLE_PROP(pinctrl7, "pinctrl-7", NULL)
> >     drivers/of/property.c:DEFINE_SIMPLE_PROP(pinctrl8, "pinctrl-8", NULL)
> >
> > Looks fragile, especially since we now have:
> >
> >     arch/arm64/boot/dts/microchip/sparx5_pcb134_board.dtsi:
> > pinctrl-9 = <&i2cmux_9>;
> >     arch/arm64/boot/dts/microchip/sparx5_pcb134_board.dtsi: pinctrl-10
> > = <&i2cmux_10>;
> >     arch/arm64/boot/dts/microchip/sparx5_pcb134_board.dtsi: pinctrl-11
> > = <&i2cmux_11>;
> >     arch/arm64/boot/dts/microchip/sparx5_pcb134_board.dtsi: pinctrl-12
> > = <&i2cmux_pins_i>;
> 
> Checking for pinctrl-* and then verifying if * matches %d would be
> more complicated and probably more expensive compared to listing
> pinctrl-[0-8]. Especially because more than 50% of pinctrl-*
> properties in DT files are NOT pinctrl-%d. So back when we merged
> this, Rob and I agreed [0-8] was good enough for now and we can add
> more if we needed to. Also, when I checked back then, all the
> pinctrl-5+ properties ended up pointing to the same suppliers as the
> lower numbered ones. So it didn't make a difference.
> 
> Ok, I just checked linux-next all the pinctrl-9+ instances and it's
> still true that they all point to the same supplier pointed to by
> pinctrl-[0-8].
> 
> So yeah, it looks fragile, 

And feels fragile, adds into confusion, etc.
Please, consider redesigning this to be more robust.

>	but is not broken and it's more efficient
> than looking for pinctrl-%d or adding more pinctrl-xx entries. So,
> let's fix it if it actually breaks? Not going to oppose a patch if
> anyone wants to make it more complete.
> 
> > > where driver_deferred_probe_check_state() is called before the supplier
> > > has probed successfully or before deferred probe timeout has expired.
> > >
> > > So, delete the call and replace it with -ENODEV.

-- 
With Best Regards,
Andy Shevchenko