linux-kernel - Re: [PATCH v2 3/3] ARM: imx6q: switch to use pinctrl driver

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Message-ID: <20120424144826.GJ9142@game.jcrosoft.org>
Date:	Tue, 24 Apr 2012 16:48:26 +0200
From:	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
To:	Dong Aisheng <aisheng.dong@...escale.com>
Cc:	Dong Aisheng-B29396 <B29396@...escale.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linus.walleij@...ricsson.com" <linus.walleij@...ricsson.com>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"kernel@...gutronix.de" <kernel@...gutronix.de>,
	"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>
Subject: Re: [PATCH v2 3/3] ARM: imx6q: switch to use pinctrl driver

On 22:04 Tue 24 Apr     , Dong Aisheng wrote:
> On Tue, Apr 24, 2012 at 08:46:34PM +0800, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > On 22:58 Fri 20 Apr     , Dong Aisheng wrote:
> > > From: Dong Aisheng <dong.aisheng@...aro.org>
> > > 
> > > Signed-off-by: Dong Aisheng <dong.aisheng@...aro.org>
> > > 
> > > ---
> > > This is not a formal patch and is only used for test
> > > since before the pinctrl core handle dummy state is in,
> > > enable pinctrl in driver will break other platforms.
> > > 
> > > ChangeLog v1->v2:
> > > * using updated binding
> > > ---
> > >  arch/arm/boot/dts/imx6q-arm2.dts   |    2 ++
> > >  arch/arm/boot/dts/imx6q.dtsi       |   17 +++++++++++++++++
> > >  arch/arm/mach-imx/Kconfig          |    2 ++
> > >  drivers/mmc/host/sdhci-esdhc-imx.c |   12 ++++++++++++
> > >  4 files changed, 33 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/arch/arm/boot/dts/imx6q-arm2.dts b/arch/arm/boot/dts/imx6q-arm2.dts
> > > index ce1c823..68b1d8d 100644
> > > --- a/arch/arm/boot/dts/imx6q-arm2.dts
> > > +++ b/arch/arm/boot/dts/imx6q-arm2.dts
> > > @@ -44,6 +44,8 @@
> > >  				fsl,card-wired;
> > >  				vmmc-supply = <&reg_3p3v>;
> > >  				status = "okay";
> > > +				pinctrl-names = "default";
> > > +				pinctrl-0 = <&pinctrl_usdhc4_1>;
> > >  			};
> > >  
> > >  			uart4: uart@...f0000 {
> > > diff --git a/arch/arm/boot/dts/imx6q.dtsi b/arch/arm/boot/dts/imx6q.dtsi
> > > index 4905f51..8cbd88b 100644
> > > --- a/arch/arm/boot/dts/imx6q.dtsi
> > > +++ b/arch/arm/boot/dts/imx6q.dtsi
> > > @@ -386,7 +386,24 @@
> > >  			};
> > >  
> > >  			iomuxc@...e0000 {
> > > +				compatible = "fsl,imx6q-iomuxc";
> > >  				reg = <0x020e0000 0x4000>;
> > > +
> > > +				/* shared pinctrl settings */
> > > +				usdhc4 {
> > > +					pinctrl_usdhc4_1: usdhc4grp-1 {
> > > +						fsl,pins = <1386 0x17059	/* MX6Q_PAD_SD4_CMD__USDHC4_CMD */
> > > +							    1392 0x17059	/* MX6Q_PAD_SD4_CLK__USDHC4_CLK	*/
> > > +							    1462 0x17059	/* MX6Q_PAD_SD4_DAT0__USDHC4_DAT0 */
> > > +							    1470 0x17059	/* MX6Q_PAD_SD4_DAT1__USDHC4_DAT1 */
> > > +							    1478 0x17059	/* MX6Q_PAD_SD4_DAT2__USDHC4_DAT2 */
> > > +							    1486 0x17059	/* MX6Q_PAD_SD4_DAT3__USDHC4_DAT3 */
> > > +							    1493 0x17059	/* MX6Q_PAD_SD4_DAT4__USDHC4_DAT4 */
> > > +							    1501 0x17059	/* MX6Q_PAD_SD4_DAT5__USDHC4_DAT5 */
> > > +							    1509 0x17059	/* MX6Q_PAD_SD4_DAT6__USDHC4_DAT6 */
> > > +							    1517 0x17059>;	/* MX6Q_PAD_SD4_DAT7__USDHC4_DAT7 */
> > Can you on IMX have alternative onfiguration where you use as example just one
> > pin on a different pad?
> > 
> Well, it's a good question.
> If user wants to set a different pad configuration for one pin in a exist group,
> he may need to create a new group node to hold that pin settings.
> This is the limitation since we can not enumerate all available pin
> configurations.
> 
> I think what we can do may be:
> For those easy changed pins, user could define the pin configuration node in
> board dts file where devices can use one more phandle to reference it to do
> minor fixup. Then we do not need to frequently change the SoC dtsi file.
> 
> For not easy changed pins, we can just add the new group in soc dtsi file
> for people to use.
I get the same issue on at91

and was thinking to do this in DT

functions {
	rxd_pb12 {
		atmel,pin-id = <44>;
		atmel,mux = <0>;
	};

	txd_pb13 {
		atmel,pin-id = <45>;
		atmel,pull = <2>;
		atmel,mux = <0>;
	};

	txd0_pb19 {
		atmel,pin-id = <51>;
		atmel,pull = <2>;
		atmel,mux = <0>;
	};

	rxd0_pb18 {
		atmel,pin-id = <50>;
		atmel,mux = <0>;
	};

	rts0_pb17 {
		atmel,pin-id = <49>;
		atmel,mux = <1>;
	};

	cts0_pb15 {
		atmel,pin-id = <47>;
		atmel,mux = <1>;
	};
};

groups {
	dbgu {
		atmel,functions = < &rxd_pb12
				   &txd_pb13 >;
	};

	uart0_rxd_txd {
		atmel,functions = < &rxd0_pb18
				   &txd0_pb19 >;
	};

	uart0_rts_cts {
		atmel,functions = < &rxd0_pb18
				   &txd0_pb19
				   &rts0_pb17
				   &cts0_pb15 >;
	}
};

so first you describe the pin fuction and then in the group just list the phandles

if we do like this  we could have a genenric C code to handle this

for the group part

Best Regards,
J.
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