linux-kernel - RE: [PATCH v3 2/3] ARM: dts: Add i2c-arbitrator bus for exynos5250-snow

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Date:	Wed, 13 Mar 2013 16:30:09 +0900
From:	Kukjin Kim <kgene.kim@...sung.com>
To:	'Naveen Krishna Ch' <naveenkrishna.ch@...il.com>,
	'Doug Anderson' <dianders@...omium.org>
Cc:	'Wolfram Sang' <wsa@...-dreams.de>,
	'Simon Glass' <sjg@...omium.org>,
	'Naveen Krishna Chatradhi' <ch.naveen@...sung.com>,
	'Grant Likely' <grant.likely@...retlab.ca>,
	'Yuvaraj Kumar' <yuvaraj.cd@...il.com>,
	'Ben Dooks' <ben.dooks@...ethink.co.uk>,
	u.kleine-koenig@...gutronix.de,
	'Mark Brown' <broonie@...nsource.wolfsonmicro.com>,
	'Girish Shivananjappa' <girish.shivananjappa@...aro.org>,
	bhushan.r@...sung.com, sreekumar.c@...sung.com,
	'Prashanth G' <prashanth.g@...sung.com>,
	'Olof Johansson' <olof@...om.net>,
	'Daniel Kurtz' <djkurtz@...omium.org>,
	'Grant Grundler' <grundler@...omium.org>,
	'Russell King' <linux@....linux.org.uk>,
	'Rahul Sharma' <rahul.sharma@...sung.com>,
	'Thomas Abraham' <thomas.abraham@...aro.org>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: RE: [PATCH v3 2/3] ARM: dts: Add i2c-arbitrator bus for exynos5250-snow

Naveen Krishna Ch wrote:
> On 16 February 2013 04:46, Doug Anderson <dianders@...omium.org> wrote:
> > We need to use the i2c-arbitrator to talk to any of the devices on i2c
> > bus 4 on exynos5250-snow so that we don't confuse the embedded
> > controller (EC).  Add the i2c-arbitrator to the device tree.  As we
> > add future devices (keyboard, sbs, tps65090) we'll add them on top of
> > this.
> >
> > The arbitrated bus is numbered 104 simply as a convenience to make it
> > easier for people poking around to guess that it might have something
> > to do with the physical bus 4.
> >
> > The addition is split between the cros5250-common and the snow device
> > tree file since not all cros5250-class devices use arbitration.
> >
> > Signed-off-by: Doug Anderson <dianders@...omium.org>
> Tested-by: Naveen Krishna Chatradhi <ch.naveen@...sung.com>
> The patch set [v3] is tested on snow with test case which uses i2c-4 from both
> EC and AP side continuously for a more than a couple of minutes.
> 
Thanks for your test and looks good to me.

BTW, Doug, I think, this should be re-worked to use pinctrl. Can you?

Thanks.

- Kukjin

> > ---
> > Changes in v3: None
> > Changes in v2:
> > - Use new device tree property names / compatible string.
> > - Include that the GPIOs for arbitration are active low.
> >
> >  arch/arm/boot/dts/cros5250-common.dtsi |  5 ++++-
> >  arch/arm/boot/dts/exynos5250-snow.dts  | 25 +++++++++++++++++++++++++
> >  2 files changed, 29 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/boot/dts/cros5250-common.dtsi
> b/arch/arm/boot/dts/cros5250-common.dtsi
> > index 46c0980..f451375 100644
> > --- a/arch/arm/boot/dts/cros5250-common.dtsi
> > +++ b/arch/arm/boot/dts/cros5250-common.dtsi
> > @@ -58,7 +58,10 @@
> >         };
> >
> >         i2c@...A0000 {
> > -               status = "disabled";
> > +               samsung,i2c-sda-delay = <100>;
> > +               samsung,i2c-max-bus-freq = <66000>;
> > +               gpios = <&gpa2 0 3 3 0>,
> > +                       <&gpa2 1 3 3 0>;
> >         };
> >
> >         i2c@...B0000 {
> > diff --git a/arch/arm/boot/dts/exynos5250-snow.dts
> b/arch/arm/boot/dts/exynos5250-snow.dts
> > index 17dd951..d2d4b48 100644
> > --- a/arch/arm/boot/dts/exynos5250-snow.dts
> > +++ b/arch/arm/boot/dts/exynos5250-snow.dts
> > @@ -16,6 +16,10 @@
> >         model = "Google Snow";
> >         compatible = "google,snow", "samsung,exynos5250";
> >
> > +       aliases {
> > +               i2c104 = &i2c_104;
> > +       };
> > +
> >         gpio-keys {
> >                 compatible = "gpio-keys";
> >
> > @@ -29,6 +33,27 @@
> >                 };
> >         };
> >
> > +       i2c-arbitrator {
> > +               compatible = "i2c-arbitrator-cros-ec";
> > +               #address-cells = <1>;
> > +               #size-cells = <0>;
> > +
> > +               i2c-parent = <&{/i2c@...A0000}>;
> > +
> > +               ap-claim-gpio = <&gpf0 3 1 0x10000 0>;
> > +               ec-claim-gpio = <&gpe0 4 0 0x10003 0>;
> > +               slew-delay-us = <10>;
> > +               wait-retry-us = <3000>;
> > +               wait-free-us = <50000>;
> > +
> > +               /* Use ID 104 as a hint that we're on physical bus 4 */
> > +               i2c_104: i2c@0 {
> > +                       reg = <0>;
> > +                       #address-cells = <1>;
> > +                       #size-cells = <0>;
> > +               };
> > +       };
> > +
> >         /*
> >          * On Snow we've got SIP WiFi and so can keep drive strengths low to
> >          * reduce EMI.
> > --
> > 1.8.1
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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> 
> 
> 
> --
> Shine bright,
> (: Nav :)

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