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From: "Heiko Stübner" <heiko@sntech.de>
To: Rob Herring <robh@kernel.org>
Cc: Levin Du <djw@t-chip.com.cn>,
	"open list:ARM/Rockchip SoC..."
	<linux-rockchip@lists.infradead.org>,
	Wayne Chou <zxf@t-chip.com.cn>,
	devicetree@vger.kernel.org,
	Linus Walleij <linus.walleij@linaro.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: Wed, 23 May 2018 17:12:10 +0200	[thread overview]
Message-ID: <1685755.J6GI985WX3@diego> (raw)
In-Reply-To: <CAL_Jsq+_QEBWdxW=J4oVGWeokc-+nMzxzX_pgCayaxg-ehivfQ@mail.gmail.com>

Hi Rob, Levin,

sorry for being late to the party.

Am Mittwoch, 23. Mai 2018, 16:43:07 CEST schrieb Rob Herring:
> On Tue, May 22, 2018 at 9:02 PM, Levin Du <djw@t-chip.com.cn> wrote:
> > On 2018-05-23 2:02 AM, Rob Herring wrote:
> >> On Fri, May 18, 2018 at 11:52:05AM +0800, djw@t-chip.com.cn wrote:
> >>> From: Levin Du <djw@t-chip.com.cn>
> >>> 
> >>> Some GPIOs sit in the GRF_SOC_CON registers of Rockchip SoCs,
> >>> which do not belong to the general pinctrl.
> >>> 
> >>> Adding gpio-syscon support makes controlling regulator or
> >>> LED using these special pins very easy by reusing existing
> >>> drivers, such as gpio-regulator and led-gpio.
> >>> 
> >>> Signed-off-by: Levin Du <djw@t-chip.com.cn>
> >>> 
> >>> ---
> >>> 
> >>> Changes in v2:
> >>> - Rename gpio_syscon10 to gpio_mute in doc
> >>> 
> >>> Changes in v1:
> >>> - Refactured for general gpio-syscon usage for Rockchip SoCs.
> >>> - Add doc rockchip,gpio-syscon.txt
> >>> 
> >>>   .../bindings/gpio/rockchip,gpio-syscon.txt         | 41
> >>> 
> >>> ++++++++++++++++++++++
> >>> 
> >>>   drivers/gpio/gpio-syscon.c                         | 30
> >>> 
> >>> ++++++++++++++++
> >>> 
> >>>   2 files changed, 71 insertions(+)
> >>>   create mode 100644
> >>> 
> >>> Documentation/devicetree/bindings/gpio/rockchip,gpio-syscon.txt
> >>> 
> >>> diff --git
> >>> a/Documentation/devicetree/bindings/gpio/rockchip,gpio-syscon.txt
> >>> b/Documentation/devicetree/bindings/gpio/rockchip,gpio-syscon.txt
> >>> new file mode 100644
> >>> index 0000000..b1b2a67
> >>> --- /dev/null
> >>> +++ b/Documentation/devicetree/bindings/gpio/rockchip,gpio-syscon.txt
> >>> @@ -0,0 +1,41 @@
> >>> +* Rockchip GPIO support for GRF_SOC_CON registers
> >>> +
> >>> +Required properties:
> >>> +- compatible: Should contain "rockchip,gpio-syscon".
> >>> +- gpio-controller: Marks the device node as a gpio controller.
> >>> +- #gpio-cells: Should be two. The first cell is the pin number and
> >>> +  the second cell is used to specify the gpio polarity:
> >>> +    0 = Active high,
> >>> +    1 = Active low.
> >> 
> >> There's no need for this child node. Just make the parent node a gpio
> >> controller.
> >> 
> >> Rob
> > 
> > Hi Rob, it is not clear to me. Do you suggest that the grf node should be
> > a
> > gpio controller,
> > like below?
> > 
> > +    grf: syscon at ff100000 {
> > +        compatible = "rockchip,gpio-syscon", "rockchip,rk3328-grf",
> > "syscon", "simple-mfd";
> 
> Yes, but drop "rockchip,gpio-syscon" and "simple-mfd".

I would disagree quite a bit here. The grf are the "general register files",
a bunch of registers used for quite a lot of things, and so it seems
among other users, also a gpio-controller for some more random pins
not controlled through the regular gpio controllers.

For a more fully stocked grf, please see
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/rk3288.dtsi#n855
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/rockchip/rk3399.dtsi#n1338

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>;
	};

	[more other syscon sub-devices]
};


Heiko	
	



> > +        //...
> > +        gpio-controller;
> > +        #gpio-cells = <2>;
> > +        gpio,syscon-dev = <&grf 0x0428 0>;
> 
> And drop this. It may be used in the kernel, but it is not a
> documented property.
> 
> > +    };
> > 
> > or just reserve the following case in the doc?
> > 
> > +    grf: syscon at ff100000 {
> > +        compatible = "rockchip,rk3328-grf", "syscon", "simple-mfd";
> > +        //...
> > +    };
> > +
> > +    gpio_mute: gpio-mute {
> > +        compatible = "rockchip,gpio-syscon";
> > +        gpio-controller;
> > +        #gpio-cells = <2>;
> > +        gpio,syscon-dev = <&grf 0x0428 0>;
> > +    };
> > 
> > 
> > Thanks
> > Levin
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe devicetree" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html

  reply	other threads:[~2018-05-23 15:12 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 [this message]
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
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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