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Date: Thu, 15 Mar 2012 11:02:07 +0800
From: Dong Aisheng <aisheng.dong@...escale.com>
To: "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>
CC: Dong Aisheng-B29396 <B29396@...escale.com>,
Grant Likely <grant.likely@...retlab.ca>,
"devicetree-discuss@...ts.ozlabs.org"
<devicetree-discuss@...ts.ozlabs.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
Guo Shawn-R65073 <r65073@...escale.com>,
"kernel@...gutronix.de" <kernel@...gutronix.de>,
"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
"cjb@...top.org" <cjb@...top.org>,
"rdunlap@...otime.net" <rdunlap@...otime.net>,
"vinod.koul@...ux.intel.com" <vinod.koul@...ux.intel.com>
Subject: Re: [PATCH v1 1/5] ARM: imx28: add basic dt support
On Wed, Mar 14, 2012 at 10:16:43PM +0800, s.hauer@...gutronix.de wrote:
> 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@...escale.com> wrote:
> > > > From: Dong Aisheng <dong.aisheng@...aro.org>
> > > >
> > > > This patch includes basic dt support which can boot via nfs rootfs.
> > > >
> > > > Signed-off-by: Dong Aisheng <dong.aisheng@...aro.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@...80000 {
> > > > + fec@...f0000 {
> > > > + 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...
>
But comparing to use an invalid value, why not just do not define that
local-mac-address property?
Regards
Dong Aisheng
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