Re: [PATCH v1 1/5] ARM: imx28: add basic dt support

["s.hauer@pengutronix.de" <s.hauer@pengutronix.de>]

On Wed, Mar 14, 2012 at 08:45:23PM +0800, Dong Aisheng wrote:
> On Wed, Mar 14, 2012 at 01:23:51AM +0800, Grant Likely wrote:
> > On Tue, 13 Mar 2012 16:47:04 +0800, Dong Aisheng <b29396@freescale.com> wrote:
> > > From: Dong Aisheng <dong.aisheng@linaro.org>
> > > 
> > > This patch includes basic dt support which can boot via nfs rootfs.
> > > 
> > > Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
> > > ---
> > >  Documentation/devicetree/bindings/arm/fsl.txt |    4 +
> > >  arch/arm/boot/dts/imx28-evk.dts               |   31 +++++++++
> > >  arch/arm/boot/dts/imx28.dtsi                  |   88 +++++++++++++++++++++++++
> > >  arch/arm/mach-mxs/Kconfig                     |    9 +++
> > >  arch/arm/mach-mxs/Makefile                    |    1 +
> > >  arch/arm/mach-mxs/imx28-dt.c                  |   67 +++++++++++++++++++
> > >  6 files changed, 200 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/arm/fsl.txt b/Documentation/devicetree/bindings/arm/fsl.txt
> > > index 54bddda..9f21faf 100644
> > > --- a/Documentation/devicetree/bindings/arm/fsl.txt
> > > +++ b/Documentation/devicetree/bindings/arm/fsl.txt
> > > @@ -1,6 +1,10 @@
> > >  Freescale i.MX Platforms Device Tree Bindings
> > >  -----------------------------------------------
> > >  
> > > +i.MX28 Evaluation Kit
> > > +Required root node properties:
> > > +    - compatible = "fsl,imx28-evk", "fsl,imx28";
> > > +
> > >  i.MX51 Babbage Board
> > >  Required root node properties:
> > >      - compatible = "fsl,imx51-babbage", "fsl,imx51";
> > > diff --git a/arch/arm/boot/dts/imx28-evk.dts b/arch/arm/boot/dts/imx28-evk.dts
> > > new file mode 100644
> > > index 0000000..9758dc4
> > > --- /dev/null
> > > +++ b/arch/arm/boot/dts/imx28-evk.dts
> > > @@ -0,0 +1,31 @@
> > > +/*
> > > + * Copyright 2012 Freescale Semiconductor, Inc.
> > > + *
> > > + * The code contained herein is licensed under the GNU General Public
> > > + * License. You may obtain a copy of the GNU General Public License
> > > + * Version 2 or later at the following locations:
> > > + *
> > > + * http://www.opensource.org/licenses/gpl-license.html
> > > + * http://www.gnu.org/copyleft/gpl.html
> > > + */
> > > +
> > > +/dts-v1/;
> > > +/include/ "imx28.dtsi"
> > > +
> > > +/ {
> > > +	model = "Freescale i.MX28 Evaluation Kit";
> > > +	compatible = "fsl,imx28-evk", "fsl,imx28";
> > > +
> > > +	memory {
> > > +		device_type = "memory";
> > > +		reg = <0x40000000 0x08000000>;
> > > +	};
> > > +
> > > +	ahb@80080000 {
> > > +		fec@800f0000 {
> > > +			phy-mode = "rmii";
> > > +			local-mac-address = [00 04 9F 01 7D 5B];
> > 
> > Generally a bad idea to put a specific mac address into the device tree.
> > Better to fill it with zeros.  Otherwise all the dev boards will end up using
> > the same value.
> > 
> Yes, this issue also exists on other platfroms like mx6q.
> One way is to dynamically get mac address by reading otp register as non-dt does
> like:
> static int __init mx28evk_fec_get_mac(void)
> {
>         int i;
>         u32 val;
>         const u32 *ocotp = mxs_get_ocotp();
> 
>         if (!ocotp)
>                 return -ETIMEDOUT;
> 
>         /*
>          * OCOTP only stores the last 4 octets for each mac address,
>          * so hard-code Freescale OUI (00:04:9f) here.
>          */
>         for (i = 0; i < 2; i++) {
>                 val = ocotp[i];
>                 mx28_fec_pdata[i].mac[0] = 0x00;
>                 mx28_fec_pdata[i].mac[1] = 0x04;
>                 mx28_fec_pdata[i].mac[2] = 0x9f;
>                 mx28_fec_pdata[i].mac[3] = (val >> 16) & 0xff;
>                 mx28_fec_pdata[i].mac[4] = (val >> 8) & 0xff;
>                 mx28_fec_pdata[i].mac[5] = (val >> 0) & 0xff;
>         }
> 
>         return 0;
> }
> 
> But it seems this needs pass mac address to fec driver via platforom data which is
> not friendly to dt.
> 
> Another way may be changing fec driver to get the fixed part of mac address(first
> two bytes) from device tree and read the left dynamical part from otp which i'm not
> sure is better enough.
> 
> BTW, filling with zeros seems not work since it's invalid mac address.

Yes, that's the idea of using this value...

Sascha

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