Re: RFC: Platform data for onboard USB assets

Greg KH
2011-03-11T17:24:04Z

On Fri, Mar 11, 2011 at 05:08:07PM +0000, Mark Brown wrote:
> On Fri, Mar 11, 2011 at 08:56:42AM -0800, Greg KH wrote:
> > On Fri, Mar 11, 2011 at 04:48:50PM +0000, Mark Brown wrote:
>
> > > USB itself is discoverable but the when the USB bus you're looking at is
> > > one that's soldered down onto a board in a specific design all bets are
> > > off regarding how complete the information you get will be. On a basic
> > > level the designers may have done things like omit the configuration
> > > EEPROMs that would set the device IDs that the driver should be relying
> > > on to identify the hardware configuration. There may be other, nastier,
> > > things going on.
>
> > Then you use the existing platform data for your USB host controller
> > driver. Doesn't that work today just fine?
>
> Wrong end of the bus. This stuff is simple enough to deal with in a
> system specific fashion, the standard solution would be to patch the
> relevant drivers to hard code whatever is required.

What drivers need this? Specifics please.

> > > You really can't make this assumption about discoverable buses on
> > > embedded devices. The discoverability will get you most of the way
> > > there but not always all of the way there.
>
> > Then the bus is not really USB, sorry. USB is discoverable, _and_ can
> > support enumeration in non-deterministic ways. If people are using it
> > in other ways then it is not USB and is something else.
>
> That's certainly a valid way of looking at things but it doesn't really
> move mainline support for systems which do stuff like this forward.

I would brand these types of systems "extremely broken" :)

Anyway, specifics are the best way forward if anyone has such a messed
up system.

thanks,

greg k-h