Messages in this thread | | | Date | Fri, 11 Mar 2011 16:26:58 +0000 | From | Andy Green <> | Subject | Re: RFC: Platform data for onboard USB assets |
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On 03/11/2011 04:03 PM, Somebody in the thread at some point said: > On Fri, Mar 11, 2011 at 04:54:03PM +0100, Arnd Bergmann wrote: >> On Friday 11 March 2011, Mark Brown wrote: > >>> It's arguable if this stuff is broken at all, from a hardware design >>> point of view it's perfectly reasonable and if you're shipping volumes >>> in the millions very small savings add up to interesting numbers easily. > >> It may be reasonable if you don't expect anyone to connect the >> device to an ethernet port, but in that case you could save much >> more by removing the ethernet chip and the socket along with the >> eeprom. > >> Really, any machine without a fixed MAC address is a huge pain >> for users, just google for "pandaboard mac address" to see >> how much work this has caused people. > > I'm not familiar with the Pandaboard but most of the devices I've worked > with that do this have unique MAC addresses but they store in other > locations on the device (typically in flash). > > Like I say, it's not just MAC addresses that can need configuring this > way - it can be other random "you're wired up this way" type > information that would normally be figured out from the USB IDs.
Yes that's exactly why I was thinking it's a class of requirement that could reasonably be a little API and extending platform_data to it. So anyone with onboard USB device can take advantage if they need to, because I guess we see gradually more boards like that.
The driver knows well all about the actual device, but there is a class of configuration information that is defined by the physical board itself - as you say "how it is wired" - and needs to be passed into the driver to inform it of its "functional configuration". When that functional configuration information is a feature of the board alone, actually the board definition file is the right place for it.
-Andy
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