Re: PATCH: ohci-s3c2410 suspend/resume support

On Tuesday 13 February 2007 11:20 am, Matt Reimer wrote:
> On 2/12/07, David Brownell <[email protected]> wrote:
> > On Monday 12 February 2007 12:53 pm, Matt Reimer wrote:
> > > Attached is a patch against 2.6.20 to implement suspend/resume support
> > > for ohci-s3c2410, based on the suspend/resume support in ohci-pxa27x.c
> > > and ohci-omap.c.
> >
> > I can't translate that description into behavior.
> >
> > Is this basically turning the controller off, so that resume
> > sees a controller reset and everything re-initializes?
> >
> > Or is it a real USB suspend state, from which the OHCI
> > controller can issue system wakeup events, and which
> > preserves device power sessions?
> 
> This patch explicitly preps the controller and turns it off. As I read
> the S3C2410 documentation, both USB host and device are powered off
> when the cpu is suspended, regardless of whether the clocks are left
> on before the suspend, so I don't think it's possible for USB to
> trigger a wake-up.

OK.  Then please update this patch with a comment to that effect:
saying that USB is completely disabled during S3C low power states,
all state explicitly discarded.


> So given that situation, is the call to usb_hcd_resume_root_hub() necessary?

If you test it and it behaves without that call, then no.
The usbcore semantics in that area have certainly changed
more than enough times that it's hard to keep track!

- Dave

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