Re: RFC: Platform data for onboard USB assets

From: Mark Brown
Date: Thu Mar 17 2011 - 17:24:57 EST

On Thu, Mar 17, 2011 at 01:26:14PM -0700, Greg KH wrote:
> On Thu, Mar 17, 2011 at 08:18:35PM +0000, Mark Brown wrote:

> > It's going to be an off the shelf USB ethernet controller. I'd be
> > astonished if the board-configurable device IDs weren't set from the
> > same SEPROM that the MAC address is so it'd just show up as a generic
> > chip of whatever kind.

> Huh? All USB controllers you buy have the ability to set the vendor and
> product id, so you should always be able to key off of that.

> Isn't that the case here?

They generally the same facility that includes the ability to set the
MAC address so if one's not been provided it seems optimistic to expect
the other.

The way this is normally done is that the ethernet controller can be
attached to a SEPROM which it reads when it powers on. This will
contain a number of device configuration parameters, including the
vendor IDs and the MAC address, which will be configured before the
device makes itself available on the bus. If the system integrator has
omitted the SEPROM then the device will come up with defaults, usually
something like all zeros.
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