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From: Linus Walleij <linus.walleij@linaro.org>
To: "Heiko Stübner" <heiko@sntech.de>
Cc: Rob Herring <robh@kernel.org>, Levin Du <djw@t-chip.com.cn>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>,
	Wayne Chou <zxf@t-chip.com.cn>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 2/5] gpio: syscon: Add gpio-syscon for rockchip
Date: Thu, 24 May 2018 10:47:59 +0200	[thread overview]
Message-ID: <CACRpkdYrHyGmMOi-qNTRxC=TR1wMnM30PxdHfNAApmZ0ucnjJg@mail.gmail.com> (raw)
In-Reply-To: <2044895.BqI5yRtle6@diego>

On Thu, May 24, 2018 at 10:35 AM, Heiko Stübner <heiko@sntech.de> wrote:
> Am Donnerstag, 24. Mai 2018, 10:28:44 CEST schrieb Linus Walleij:
>> On Wed, May 23, 2018 at 5:12 PM, Heiko Stübner <heiko@sntech.de> wrote:
>> > So the gpio controller should definitly also be a subnode.
>> >
>> > The gpio in question is called "mute", so I'd think the gpio-syscon driver
>> > should just define a "rockchip,rk3328-gpio-mute" compatible and contain
>> > all the register voodoo in the driver itself and not define it in the dt.
>> >
>> > So it should probably look like
>> >
>> > grf: syscon at ff100000 {
>> >
>> >         compatible = "rockchip,rk3328-grf", "syscon", "simple-mfd";
>> >
>> >         [all the other syscon sub-devices]
>> >
>> >         gpio_mute: gpio-mute {
>> >
>> >                 compatible = "rockchip,rk3328-gpio-mute";
>> >                 gpio-controller;
>> >                 #gpio-cells = <2>;
>> >
>> >         };
>>
>> I'm sceptic.
>>
>> That doesn't sound like "general purpose input output" at all.
>>
>> It sounds like special purpose, for a mute button.
>>
>> Does it use IRQ? I would recommend implementing
>> drivers/input/keyboard/syscon-keys.c in the same vein
>> as drivers/leds/leds-syscon.c so you can avoid indirection
>> through GPIO for no good reason at all.
>
> To quote Levin from the other mail:
> --------
> The "mute" pin is a output only GPIO, which is already supported by
> setting flags in the gpio-syscon
>   driver. And yes, this pin has a defined function, but can also be used
> for general purpose operation.
> --------
>
> So to summarize, the documentation calls it "mute", but it is usable as
> a general pin, which is the reason Levin is working on it - because on his
> board this pin is used to switch between two voltages (aka a gpio-regulator)
> for the sdmmc controller [3.3V + 1.8V].

OK then, I was wrong! :)

Go ahead with this, sorry for the fuzz.

Yours,
Linus Walleij

  reply	other threads:[~2018-05-24  8:48 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-18  3:32 [PATCH v2 0/5] Add sdmmc UHS support to ROC-RK3328-CC board djw
2018-05-18  3:52 ` [PATCH v2 1/5] gpio: syscon: allow fetching syscon from parent node djw
2018-05-18  3:52   ` [PATCH v2 2/5] gpio: syscon: Add gpio-syscon for rockchip djw
2018-05-22 18:02     ` Rob Herring
2018-05-23  2:02       ` Levin Du
2018-05-23 14:43         ` Rob Herring
2018-05-23 15:12           ` Heiko Stübner
2018-05-23 19:53             ` Rob Herring
2018-05-24  1:59               ` Levin Du
2018-05-24 12:18                 ` Heiko Stuebner
2018-05-28  3:34                   ` Levin
2018-05-24 12:07               ` Heiko Stuebner
2018-05-24 13:38                 ` Rob Herring
2018-05-24  8:28             ` Linus Walleij
2018-05-24  8:35               ` Heiko Stübner
2018-05-24  8:47                 ` Linus Walleij [this message]
2018-05-18  3:52   ` [PATCH v2 3/5] arm64: dts: rockchip: Add gpio-mute to rk3328 djw
2018-05-18  3:52   ` [PATCH v2 4/5] arm64: dts: rockchip: Add io-domain to roc-rk3328-cc djw
2018-05-18  3:52   ` [PATCH v2 5/5] arm64: dts: rockchip: Add sdmmc UHS support for roc-rk3328-cc djw
2018-05-23  8:08   ` [PATCH v2 1/5] gpio: syscon: allow fetching syscon from parent node Linus Walleij

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