Alfred, On Wed, Nov 18, 2009 at 5:54 PM, alfred steele <[email protected]>wrote:
> On Mon, Nov 16, 2009 at 8:59 PM, Ben Warren <[email protected]> > wrote: > > Hi Alfred, > > > > alfred steele wrote: > >>> > >>> Thanks for your submission! > >>> > >> > >> What is the current design on the mxc fec interface's attainment of a > >> MAC address. From the kernel driver it looks like it looks at the > >> IIM(IC identification registers) on the MXC platform(like mx51/35) to > >> look for a programmed mac address and then the set the fec mac to the > >> same . > >> > >> Looks like with the current mxc_fec driver there is not support for > >> the same. I am thinking of a mechanism to hardcode a fake MAC which > >> would subsequently be picked up by the kernel without using the > >> bd_info structure. > >> Any comments/suggestions? > >> > >> -Alfred. > >> > > > > I don't know much about this driver, but it appears to be doing things > > incorrectly. The correct flow is as follows. It is documented in > > 'doc/README.enetaddr': > > > > 1. The driver's initialize() function read from NVRAM if available. MAC > > address is stuffed into dev->enetaddr. The initialize() function should > not > > try to get the address from the environment, which is where the imx27 > driver > > goes wrong. > > 2. After all drivers have been initialized, eth_initialize() ( in > net/eth.c) > > reads from the environment. If the value in the environment is valid and > > the value in dev->enetaddr is valid and both are different, the user is > > warned. The value in the environment overwrites the value in > dev->enetaddr > > 3. When a network operation is performed, the driver's init() function is > > called, which is where the address is programmed into the device. > > > > As you can see, if the device is never used, step 3 is never exected and > the > > device is never programmed. This is how it's supposed to work, since the > > U-boot design philosophy dictates that hardware is never touched unless > it > > is used in U-boot. I'm pretty sure hard-coding a fake MAC address would > run > > afoul of this rule. > Is there a way to pass the information to kernel using either the > dev->enetaddr without programming the IIM module register. Would i > have to use bd_info structure or can we do without it.? This problem > is specific to the mx27 i guess. > -Alfred > I'm pretty sure it's a much-discussed ARM peculiarity. Not at all my area of expertise, so I'll leave it to others to suggest options. regards, Ben
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