linux-kernel - RE: [PATCH 2/6] ARM: davinci: da850: add DT node for I2C0

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Date:	Mon, 28 Jan 2013 05:17:28 +0000
From:	"Vishwanathrao Badarkhe, Manish" <manishv.b@...com>
To:	"Nori, Sekhar" <nsekhar@...com>
CC:	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"davinci-linux-open-source@...ux.davincidsp.com" 
	<davinci-linux-open-source@...ux.davincidsp.com>,
	Kevin Hilman <khilman@...prootsystems.com>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"sameo@...ux.intel.com" <sameo@...ux.intel.com>,
	"tony@...mide.com" <tony@...mide.com>,
	"broonie@...nsource.wolfsonmicro.com" 
	<broonie@...nsource.wolfsonmicro.com>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	"grant.likely@...retlab.ca" <grant.likely@...retlab.ca>,
	"rob@...dley.net" <rob@...dley.net>,
	"AnilKumar, Chimata" <anilkumar@...com>, "hs@...x.de" <hs@...x.de>
Subject: RE: [PATCH 2/6] ARM: davinci: da850: add DT node for I2C0

On Fri, Jan 25, 2013 at 16:20:13, Nori, Sekhar wrote:
> On 1/24/2013 5:05 PM, Vishwanathrao Badarkhe, Manish wrote:
> > Add I2C0 device tree node information to da850-evm.
> > Also, add I2C0 pin muxing information in da850-evm.
> > 
> > Signed-off-by: Vishwanathrao Badarkhe, Manish <manishv.b@...com>
> > ---
> > Depends on patch
> > http://comments.gmane.org/gmane.linux.davinci/25993
> > 
> >  arch/arm/boot/dts/da850-evm.dts |   15 +++++++++++++++
> >  arch/arm/boot/dts/da850.dtsi    |   10 ++++++++++
> >  2 files changed, 25 insertions(+), 0 deletions(-)
> > 
> > diff --git a/arch/arm/boot/dts/da850-evm.dts 
> > b/arch/arm/boot/dts/da850-evm.dts index 8cac9d2..3d8290a 100755
> > --- a/arch/arm/boot/dts/da850-evm.dts
> > +++ b/arch/arm/boot/dts/da850-evm.dts
> > @@ -27,5 +27,20 @@
> >  		serial2: serial@...d000 {
> >  			status = "okay";
> >  		};
> > +		i2c0@...2000 {
> 
> This should be
> 		i2c0: i2c@...2000
> 
> to follow the convention elsewhere in file.

Ok, I will change this in next version.

> 
> > +			status = "okay";
> > +		};
> > +	};
> > +};
> > +&pmx_core {
> > +	pinctrl-names = "default";
> > +	pinctrl-0 = <
> > +		&i2c0_pins
> > +	>;
> > +
> > +	i2c0_pins: pinmux_i2c0_pins{
> > +		pinctrl-single,bits = <
> > +			0x10 0x00002200 0x0000ff00	/* I2C0_SDA,I2C0_SCL */
> > +		>;
> 
> This should go into the dtsi file. See the discussion on NAND DT support submitted by Anil Kumar.

I have seen Anil Kumar's discussion for pin-muxing which includes Linus patch of grab pin 
control handles from device core at following location:
http://lkml.indiana.edu/hypermail/linux/kernel/1301.2/00094.html

I have done changes accordingly for I2C0 pin muxing and seen kernel crashes giving message 
like "i2c_davinci i2c_davinci.1: could not find pctldev for node /soc/
pinmux@...4120/pinmux_i2c0_pins, deferring probe". This is happened because I2C0 driver 
gets probed before pin mux driver.
  
To resolve this issue, I made changes in code to ensure pin control driver gets probed before 
I2C0 driver by registering pin control driver during arch_init call.
 
Hence, in order to move I2C0 pin muxing in dtsi file above fix is required.
> 
> Thanks,
> Sekhar
> 
> PS: You are using an old address for Kevin Hilman. The MAINTAINERS file has been updated for a long time now. Liam's address is also wrong but I don't have his updated e-mail.
> 


Regards, 
Manish