Alfred,
On Wed, Nov 18, 2009 at 5:54 PM, alfred steele alfred.jaquez@gmail.comwrote:
On Mon, Nov 16, 2009 at 8:59 PM, Ben Warren biggerbadderben@gmail.com 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':
- 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
- 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