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    SubjectRe: [PATCH v1 1/5] ARM: imx28: add basic dt support
    On Thu, Mar 15, 2012 at 07:22:04PM +0800, Lothar Waßmann wrote:
    > Hi,
    >
    > Dong Aisheng writes:
    > > 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@pengutronix.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:
    > > > [...]
    > > > > > > 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?
    > >
    > That patch sets the OUI to the Freescale owned MAC range. Thus only
    > Freescale products may be able to use the driver.
    >
    No.
    My proposal is only set the fixed part(first two octets) in board dts file,
    each board knows it's value, and read the left 4 octets from OCOTP dynamically.
    Obviously the freeescale board dts file is only for FSL platforms.
    Other platforms can define their fix part of MAC address in their dts file.

    > 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.

    > Currently I'm setting up the MAC address for our TX28 from the fuses
    > in the platform code passed via platform_data, but that will obviously
    > not work with DT.
    >
    Non-dt can also use my proposal, then you only need to pass the fixed part of
    MAC via platfrom data, the left will be read by fec driver.

    > The correct way would probably be to pass the MAC from the bootloader
    > via a DT blob. But that would require all bootloaders to be updated
    > first to support DTS. :(
    >
    But uboot will face the same problem that can not define a valid MAC
    in dts, did i undertand correctly?

    > An intermediate solution could be using OF_DEV_AUXDATA to pass a
    > platform_data struct that may contain a MAC address set up by the
    > platform code.
    >
    Yes, it's a way but i'm afraid will not get accepted by dt people.

    Regards
    Dong Aisheng

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