linux-kernel - Re: [PATCH RFC 4/6] net: rfkill: gpio: add device tree support

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Message-ID: <20140120081007.GA19123@xps8300>
Date:	Mon, 20 Jan 2014 10:10:07 +0200
From:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Chen-Yu Tsai <wens@...e.org>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Alexandre Courbot <gnurou@...il.com>,
	Arnd Bergmann <arnd@...db.de>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	Johannes Berg <johannes@...solutions.net>,
	"David S. Miller" <davem@...emloft.net>,
	devicetree <devicetree@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	linux-sunxi <linux-sunxi@...glegroups.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>
Subject: Re: [PATCH RFC 4/6] net: rfkill: gpio: add device tree support

Hi,

On Sat, Jan 18, 2014 at 12:11:56AM +0100, Linus Walleij wrote:
> On Fri, Jan 17, 2014 at 6:43 PM, Chen-Yu Tsai <wens@...e.org> wrote:
> > On Sat, Jan 18, 2014 at 12:47 AM, Arnd Bergmann <arnd@...db.de> wrote:
> 
> >>> +- NAME_shutdown-gpios  : GPIO phandle to shutdown control
> >>> +                         (phandle must be the second)
> >>> +- NAME_reset-gpios     : GPIO phandle to reset control
> >>> +
> >>> +NAME must match the rfkill-name property. NAME_shutdown-gpios or
> >>> +NAME_reset-gpios, or both, must be defined.
> >>> +
> >>
> >> I don't understand this part. Why do you include the name in the
> >> gpios property, rather than just hardcoding the property strings
> >> to "shutdown-gpios" and "reset-gpios"?
> >
> > This quirk is a result of how gpiod_get_index implements device tree
> > lookup.
> 
> Why can't it just have a single property "gpios", where the first
> element is the reset GPIO and the second is the shutdown GPIO?
> 
> rfkill-gpio does this:
> 
> gpio = devm_gpiod_get_index(&pdev->dev, rfkill->reset_name, 0);
> gpio = devm_gpiod_get_index(&pdev->dev, rfkill->shutdown_name, 1);
> 
> The passed con ID name parameter is only there for the device
> tree case it seems. (ACPI ignores it.) So what about you just
> don't pass it at all and patch it to do like this instead:
> 
> gpio = devm_gpiod_get_index(&pdev->dev, NULL, 0);
> gpio = devm_gpiod_get_index(&pdev->dev, NULL, 1);
> 
> Heikki, are you OK with this change?

Yes, definitely. That is much cleaner.

Thanks,

-- 
heikki
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