RE: [RFC PATCH 2/5] OMAP2+: add cpu id register to MAC addresshelper

[Premi, Sanjeev]

> -----Original Message-----
> From: linux-omap-owner@xxxxxxxxxxxxxxx 
> [mailto:linux-omap-owner@xxxxxxxxxxxxxxx] On Behalf Of Arnd Bergmann
> Sent: Friday, March 18, 2011 2:05 PM
> To: Andy Green
> Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx; 
> linux-omap@xxxxxxxxxxxxxxx; 
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; patches@xxxxxxxxxx; Andy Green
> Subject: Re: [RFC PATCH 2/5] OMAP2+: add cpu id register to 
> MAC address helper
> 
> On Saturday 12 March 2011, Andy Green wrote:
> > Introduce a generic helper function that can set a MAC address using
> > data from the OMAP unqiue CPU ID register.
> > 
> > Signed-off-by: Andy Green <andy.green@xxxxxxxxxx>
> > ---
> > 
> >  arch/arm/mach-omap2/id.c              |   13 +++++++++++++
> >  arch/arm/mach-omap2/include/mach/id.h |    1 +
> >  2 files changed, 14 insertions(+), 0 deletions(-)
> > 
> > diff --git a/arch/arm/mach-omap2/id.c b/arch/arm/mach-omap2/id.c
> > index 5f9086c..fc69ec5 100644
> > --- a/arch/arm/mach-omap2/id.c
> > +++ b/arch/arm/mach-omap2/id.c
> > @@ -506,3 +506,16 @@ void __init 
> omap2_set_globals_tap(struct omap_globals *omap2_globals)
> >         else
> >                 tap_prod_id = 0x0208;
> >  }
> > +
> > +
> > +void omap2_die_id_to_mac(u8 *mac, int length)
> > +{
> > +       struct omap_die_id odi;
> > +
> > +       omap_get_die_id(&odi);
> > +       memcpy(mac, &odi.id_0, length);
> > +
> > +       /* mark it as not multicast and outside official 
> 80211 MAC namespace */
> > +
> > +       mac[0] = (mac[0] & ~1) | 2;
> > +}
> 
> This is a pretty clever trick, but it's not an official 
> globally unique MAC
> address, right?

[sp] This 'trick' has been tried earlier in u-boot. See:
     http://www.mail-archive.com/u-boot@xxxxxxxxxxxxx/msg19915.html

     I am also not sure whether DIE_ID would really be unique.

~sanjeev

> Maybe we can ask TI to officially request a 
> MAC address range
> for OMAP SoCs and document an official procedure to compute it.
> 
> 	Arnd
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