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

[Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>]

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On Mon, 19 Mar 2012 17:49:02 +0100, Lothar Waßmann <LW-bxm8fMRDkQLDiMYJYoSAnRvVK+yQ3ZXh@public.gmane.org> wrote:
> Hi,
> 
> Grant Likely writes:
> > On Mon, 19 Mar 2012 07:54:33 +0100, Lothar Waßmann <LW-bxm8fMRDkQLDiMYJYoSAnRvVK+yQ3ZXh@public.gmane.org> wrote:
> > > Grant Likely writes:
> > > > On Fri, 16 Mar 2012 11:01:35 +0800, Dong Aisheng <aisheng.dong-KZfg59tc24xl57MIdRCFDg@public.gmane.org> wrote:
> > > > > On Thu, Mar 15, 2012 at 07:22:04PM +0800, Lothar Waßmann wrote:
> > > > > > Dong Aisheng writes:
> > > > > > > On Thu, Mar 15, 2012 at 02:53:29PM +0800, Lothar Waßmann wrote:
> > > > > > Anyway there is no definite spec how the MAC address(es) are stored
> > > > > > in the fuse map. Thus reading the MAC from there is more or less
> > > > > > platform specific.
> > > > > > 
> > > > > It's just provide one more option since there are customers storing the MAC
> > > > > in the fuse map.
> > > > 
> > > > That should be straight forward to support; have a property that
> > > > specifies the method used for fetching/calculating the MAC.
> > > > 
> > > Executable code stored inside a DT blob? ;)
> > 
> > I know you're joking here, but I'm going to answer seriously
> > anyway... Absolutely not.  What I'm suggesting is a property that
> > specifies the method used to determine the mac address.  Something
> > like (off the top of my head):
> > 
> > 	local-mac-address = [01 02 03 00 00 00];
> > 	local-mac-mask = [0xff 0xff 0xff 0 0 0];
> > 	mac-encoding = "append-serial-number";
> > 
> That still does not specify where the remaining part of the MAC is
> stored and how it should be retrieved.

I'm suggesting that you define a string that means something specific;
that hopefully can be shared by multiple platforms.  For example,
"append-serial-number" might mean start with the values selected by
AND of local-mac-address and local-mac-mask, and OR in the board's
serial number.  You would need to define something that worked if this
was the solution you used.

> > Okay, if so then it would be wise to have a reliable function for the
> > MAC driver to call to lookup it's address as determined by platform
> > code.  Alternately, the platform code can write the correct mac
> > address into the device tree node at init time (see
> > prom_update_property() and prom_add_property()).
> > 
> That sounds good. Didn't know about those functions. That could be
> used to mimic the current behaviour of supplying the MAC via
> platform_data.

I'm okay with doing this; but make sure you remove the bogus
local-mac-address from the .dts file.

g.


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