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Re: [GIT PULL] On-demand device probing

From Russell King - ARM Linux <linux@arm.linux.org.uk>
Newsgroups linux.kernel
Subject Re: [GIT PULL] On-demand device probing
Date 2015-10-19 17:50 +0200
Message-ID <qlkRd-ll-35@gated-at.bofh.it> (permalink)
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On Mon, Oct 19, 2015 at 04:29:40PM +0100, David Woodhouse wrote:
> I don't know that there *is* a coherent plan here to address it all.
> 
> Certainly, we *will* need subsystems to have firmware-specific
> knowledge in some cases. Take GPIO as an example; ACPI *has* a way to
> describe GPIO, and properties which reference GPIO pins are intended to
> work through that — while in DT, properties which reference GPIO pins
> will have different contents. They'll be compatible at the driver
> level, in the sense that there's a call to get a given GPIO given the
> property name, but the subsystems *will* be doing different things
> behind the scenes.

It's a bit ironic that you've chosen GPIO as an example there.  The
"new" GPIO API (the gpiod_* stuff) only has a fwnode way to get the
gpio descriptor.  There's no of_* method.

I'd like to use the gpiod_* stuff, but I feel that my options are
rather limited: either use fwnode_get_named_gpiod() with
&dev->of_node->fwnode, which seems like a hack by going underneath
the covers of how fwnode is (partially) implemented with DT, or by
using of_get_named_gpio() and the converting the gpio number to a
descriptor via gpio_to_desc().  Both feel very hacky.

If ACPI already handles GPIOs internally, then I'm left wondering
why GPIO descriptor stuff went down the fwnode route at all - it
seems rather pointless in this case, and it seems to make the use
of the gpiod* interfaces where we _do_ need to use it (DT) harder
and more hacky.

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Thread

Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-18 21:40 +0200
  Re: [GIT PULL] On-demand device probing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-18 21:40 +0200
    Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-18 22:00 +0200
      Re: [GIT PULL] On-demand device probing David Woodhouse <dwmw2@infradead.org> - 2015-10-19 11:50 +0200
        Re: [GIT PULL] On-demand device probing Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-19 12:00 +0200
        Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-19 13:10 +0200
        Re: [GIT PULL] On-demand device probing Rob Herring <robh+dt@kernel.org> - 2015-10-19 14:40 +0200
          Re: [GIT PULL] On-demand device probing David Woodhouse <dwmw2@infradead.org> - 2015-10-19 14:50 +0200
            Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-19 17:00 +0200
              Re: [GIT PULL] On-demand device probing David Woodhouse <dwmw2@infradead.org> - 2015-10-19 17:40 +0200
                Re: [GIT PULL] On-demand device probing Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-19 17:50 +0200
                Re: [GIT PULL] On-demand device probing Uwe Kleine-König   <u.kleine-koenig@pengutronix.de> - 2015-10-19 20:30 +0200
                Re: [GIT PULL] On-demand device probing Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-19 20:50 +0200
                Re: [GIT PULL] On-demand device probing Alexandre Courbot <gnurou@gmail.com> - 2015-10-20 01:50 +0200
                Re: gpiod API considerations [Was: [GIT PULL] On-demand device  probing] Uwe Kleine-König   <u.kleine-koenig@pengutronix.de> - 2015-10-20 09:20 +0200
                Re: [GIT PULL] On-demand device probing David Woodhouse <dwmw2@infradead.org> - 2015-10-20 13:20 +0200
                Re: [GIT PULL] On-demand device probing Rob Herring <robh+dt@kernel.org> - 2015-10-19 18:00 +0200
                Re: [GIT PULL] On-demand device probing "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-19 23:20 +0200
                Re: [GIT PULL] On-demand device probing Rob Herring <robh@kernel.org> - 2015-10-20 01:00 +0200
                Re: [GIT PULL] On-demand device probing "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-20 09:30 +0200
                Re: [GIT PULL] On-demand device probing Rob Herring <robh@kernel.org> - 2015-10-20 16:20 +0200
                Re: [GIT PULL] On-demand device probing Alan Stern <stern@rowland.harvard.edu> - 2015-10-20 16:50 +0200
                Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-20 17:40 +0200
                Re: [GIT PULL] On-demand device probing Alan Stern <stern@rowland.harvard.edu> - 2015-10-20 18:10 +0200
                Re: [GIT PULL] On-demand device probing Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-10-20 18:30 +0200
                Re: [GIT PULL] On-demand device probing Alan Stern <stern@rowland.harvard.edu> - 2015-10-20 19:20 +0200
                Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-20 21:40 +0200
                Re: [GIT PULL] On-demand device probing "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-21 01:10 +0200
                Re: [GIT PULL] On-demand device probing Jean-Francois Moine <moinejf@free.fr> - 2015-10-21 08:20 +0200
                Re: [GIT PULL] On-demand device probing "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-22 02:30 +0200
                Re: [GIT PULL] On-demand device probing Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-10-22 11:20 +0200
                Re: [GIT PULL] On-demand device probing "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-27 05:40 +0100
                Re: [GIT PULL] On-demand device probing "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-21 01:10 +0200
                Re: [GIT PULL] On-demand device probing Geert Uytterhoeven <geert@linux-m68k.org> - 2015-10-21 11:00 +0200
                Re: [GIT PULL] On-demand device probing "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-22 01:20 +0200
                Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-19 18:10 +0200
      Re: [GIT PULL] On-demand device probing Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-10-19 14:40 +0200
        Re: [GIT PULL] On-demand device probing Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-19 15:20 +0200
          Re: [GIT PULL] On-demand device probing Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-10-19 16:20 +0200
            Re: [GIT PULL] On-demand device probing Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-19 16:40 +0200
              Re: [GIT PULL] On-demand device probing Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-10-19 17:10 +0200
                Re: [GIT PULL] On-demand device probing Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-19 17:40 +0200
                Re: [GIT PULL] On-demand device probing Geert Uytterhoeven <geert@linux-m68k.org> - 2015-10-19 18:30 +0200
                Re: [GIT PULL] On-demand device probing Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-19 18:50 +0200
                Re: Alternative approach to solve the deferred probe (was: [GIT  PULL] On-demand device probing) Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-20 17:50 +0200
                Re: Alternative approach to solve the deferred probe Frank Rowand <frowand.list@gmail.com> - 2015-10-21 06:00 +0200
                Re: Alternative approach to solve the deferred probe Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-21 10:20 +0200
                Re: Alternative approach to solve the deferred probe Frank Rowand <frowand.list@gmail.com> - 2015-10-21 17:40 +0200
                Re: Alternative approach to solve the deferred probe Grygorii Strashko <grygorii.strashko@ti.com> - 2015-10-21 19:00 +0200
                Re: Alternative approach to solve the deferred probe Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-21 19:30 +0200
                Re: Alternative approach to solve the deferred probe Grygorii Strashko <grygorii.strashko@ti.com> - 2015-10-21 20:20 +0200
                Re: Alternative approach to solve the deferred probe Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-21 20:30 +0200
                Re: Alternative approach to solve the deferred probe Grygorii Strashko <grygorii.strashko@ti.com> - 2015-10-22 17:20 +0200
                Re: Alternative approach to solve the deferred probe Frank Rowand <frowand.list@gmail.com> - 2015-10-21 20:10 +0200
                Re: Alternative approach to solve the deferred probe Grygorii Strashko <grygorii.strashko@ti.com> - 2015-10-21 20:40 +0200
                Re: Alternative approach to solve the deferred probe Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-21 22:40 +0200
                Re: Alternative approach to solve the deferred probe Frank Rowand <frowand.list@gmail.com> - 2015-10-22 02:10 +0200
                Re: Alternative approach to solve the deferred probe (was: [GIT  PULL] On-demand device probing) Mark Brown <broonie@kernel.org> - 2015-10-23 01:40 +0200
        Re: [GIT PULL] On-demand device probing Frank Rowand <frowand.list@gmail.com> - 2015-10-21 18:10 +0200
          Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-21 18:30 +0200
            Re: [GIT PULL] On-demand device probing Frank Rowand <frowand.list@gmail.com> - 2015-10-21 20:30 +0200
              Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-21 23:10 +0200
              Re: [GIT PULL] On-demand device probing Rob Herring <robh+dt@kernel.org> - 2015-10-21 23:20 +0200
                Re: [GIT PULL] On-demand device probing Frank Rowand <frowand.list@gmail.com> - 2015-10-22 00:00 +0200
                Re: [GIT PULL] On-demand device probing Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-10-22 11:10 +0200
                Re: [GIT PULL] On-demand device probing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-22 16:40 +0200
                Re: [GIT PULL] On-demand device probing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-22 16:50 +0200
                Re: [GIT PULL] On-demand device probing Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-10-22 17:10 +0200
                Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-23 01:40 +0200
                Re: [GIT PULL] On-demand device probing Frank Rowand <frowand.list@gmail.com> - 2015-10-22 21:00 +0200
                Re: [GIT PULL] On-demand device probing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-10-22 21:30 +0200
                Re: [GIT PULL] On-demand device probing Tim Bird <tim.bird@sonymobile.com> - 2015-10-23 17:50 +0200
                Re: [GIT PULL] On-demand device probing Rob Herring <robh+dt@kernel.org> - 2015-10-23 18:40 +0200
                Re: [GIT PULL] On-demand device probing "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-24 15:50 +0200
                Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-25 00:10 +0200
                Re: [GIT PULL] On-demand device probing "Rafael J. Wysocki" <rafael@kernel.org> - 2015-10-25 15:00 +0100
                Re: [GIT PULL] On-demand device probing Mark Brown <broonie@kernel.org> - 2015-10-26 02:20 +0100
                Re: [GIT PULL] On-demand device probing Michael Turquette <mturquette@baylibre.com> - 2015-10-26 12:00 +0100
                Re: [GIT PULL] On-demand device probing Tomeu Vizoso <tomeu.vizoso@collabora.com> - 2015-10-26 14:00 +0100
                Re: [GIT PULL] On-demand device probing "Rafael J. Wysocki" <rafael@kernel.org> - 2015-10-27 00:40 +0100
                Re: [GIT PULL] On-demand device probing "Andrew F. Davis" <afd@ti.com> - 2015-10-25 20:50 +0100
                Re: [GIT PULL] On-demand device probing Geert Uytterhoeven <geert@linux-m68k.org> - 2015-10-24 20:00 +0200

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