[RFC][USB] powerpc: Workaround for the PPC440EPX USBH_23 errrata

[Vitaly Bordug]

В Tue, 19 Aug 2008 12:03:42 +1000
Benjamin Herrenschmidt <benh at kernel.crashing.org> пишет:

> 
>  .../...
> 
> > There is a software workaround that uses a trick to detect if
> > full-speed interface is enabled from the hi-speed driver(and vice
> > versa), and use suspend control for ohci to enable/disable it
> > appropriately. 
> > Initial version of the software workaround was posted to
> > linux-usb-devel:
> > 
> > http://www.mail-archive.com/linux-usb-devel@lists.sourceforge.net/msg54019.html
> > 
> > and later were made available from amcc.com:
> > http://www.amcc.com/Embedded/Downloads/download.html?cat=1&family=15&ins=2
> > 
> > The patch below is generally based on the latter, but reworked to
> > powerpc/of_device USB drivers, and uses a few devicetree inquiries
> > to get rid of (some) hardcoded defines.
> 
> Well, it seems to still call things based on #ifdef CONFIG_* instead
> of testing for whatever "errata" bit or flag you can initialize.
> 
> A proper approach is to have the OF probe code detect via some
> device-tree compatible testing or such, that it's indeed hitting the
> broken chip, use that to set a quirk in the controller, and then
> have the core ehci-hub.c code do whatever it has to do based on
> the presence of that quirk.
Makes sense, thanks. I'll look into rearranging stuff appropriately
over this weekend.

Thanks,
-Vitaly