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

[Dong Aisheng]

On Thu, Mar 15, 2012 at 07:24:19PM +0800, s.hauer@xxxxxxxxxxxxxx wrote:
> On Thu, Mar 15, 2012 at 06:59:28PM +0800, Dong Aisheng wrote:
> > On Thu, Mar 15, 2012 at 02:53:29PM +0800, Lothar Waßmann wrote:
> > > Hi,
> > > 
> > > Dong Aisheng writes:
> > > > On Wed, Mar 14, 2012 at 10:16:43PM +0800, s.hauer@xxxxxxxxxxxxxx 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:
> > > [...]
> > > > > > 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?
> > > > 
> > > Because a MAC address is by definition a GLOBALLY UNIQUE IDENTIFIER
> > > which is contrary to coding a "valid" default value for it somewhere!
> > > The owner of a certain MAC address range (OUI) is responsible for
> > > ensuring the uniqueness. Thus only they may assign a specific MAC
> > > address to a specific device.
> > > 
> > Yes, you're correct.
> > So i propose to read the MAC address from MX28 OTP in fec driver instead of
> > define it in device tree in my last mail.
> > http://www.spinics.net/lists/arm-kernel/msg165040.html
> > Do you have any comment on that way?
> 
> Yes, you could do that. Otherwise it's perfectly fine to pass the MAC
> address in the device tree, it's just not ok to put specific values
> into the kernel source. You could leave the values blank and let the
Yes, correct.

> bootloader fill them in. Or you could fill in valid values before you
> compile the devicetree, but be prepared for surprises once you have
> two boards in your network and use the devicetree for both.
> 

Thanks for the info.
I will submit that patch for discussion.

Regards
Dong Aisheng

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