> -----Original Message----- > From: Tim Nordell [mailto:tim.nordell@xxxxxxxxxxx] > Sent: Saturday, September 25, 2010 5:20 AM > To: Gadiyar, Anand > Cc: Benoit Cousson; linux-omap@xxxxxxxxxxxxxxx; Tony > Lindgren; Paul Walmsley; Kevin Hilman > Subject: Re: [RFC 2/5] OMAP: mux: Make low level function private > > On 09/24/10 18:09, Gadiyar, Anand wrote: > > On Fri, Sep 24, 2010 at 2:45 PM, Benoit Cousson > <b-cousson@xxxxxx> wrote: > >> omap_mux_read / omap_mux_write should not be accessed directly > >> outside the mux framework. > >> Do we really have use case that require dynamic mux change beside > >> GPIO? > >> > > > > Only case I can think of is for any workarounds for issues > that turn up. > > No such cases exist today on OMAP3 at least, and none are likely to > > appear in future (I hope). So your assumption is valid. > > > > We have a use-case here - granted the code currently is a complete hack > and not something clean enough for the mainline kernel. > > We recently rediscovered the USB3320 PHY suspend issue that is in the > errata on the OMAP35x platform (Advisory 3.1.1.193) and we came up with > a workaround for it (despite the errata saying there isn't any) where > essentially we do: > > 1) Allow the EHCI controller to suspend the PHY as normal > 2) Cut the power to the USB host controller using power domains. This > resets the logic states in the USB host controller so that it is usable > again. > 3) Remux all the pins talking to the PHY into GPIO mode > 4) Monitor said pins for changes in status to know when a remote wakeup > request occurs > 5) Remux pins back to USB PHY mode > 6) Reenable power to the USB host controller and reinitialize registers We've tried this technique before - you still need to re-enumerate after the resume, right? So you might as well just power down the PHY and you should be able to recover. Ajay Gupta did a lot of work on this - not sure if this worked well. We basically gave up on this interoperability issue and decided to work around it in newer silicon. 3630 ES1.1 and later has suspend-resume working with the SMSC PHY. - Anand -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
