Re: Tegra3 ehci_suspend and ehci_resume

Re: Tegra3 ehci_suspend and ehci_resume

[Alan Stern]

On Thu, 13 Dec 2012, Timur wrote:

> On 12/12/2012 07:34 PM, Alan Stern wrote:
> 
> > Okay.  Then how about this: Unplug both the power connector and the
> > slave connector.  After the N7 goes into deep sleep, plug the power
> > connector back in but leave the slave unplugged.  Then a few seconds
> > later, plug in the slave.
> 
> This always fails (-71 / SET_ADDRESS). The issues can then only be 
> solved, by unplugging the "OTG" adapter. In other words, by switching to 
> peripheral mode (and back).
> 
> > Also try doing the same thing, but don't wait for the N7 to go into
> > deep sleep.  If this works but the other test doesn't, then clearly the
> > slave is working correctly and the problem lies in the host controller.
> 
> This works well most of the time. Some issues in a few cases, not sure 
> why. (It is possible to debug over WiFi. But doing so would prevent LP0.)

So it seems clear that the problem is the deep sleep implementation in 
ehci-tegra.  That implementation is very non-standard in the 3.7 
kernel.

To fix it will require assistance from the people responsible for the 
ehci-tegra driver.  I can be of only limited help because I don't have 
any Tegra hardware and I don't know how it's supposed to work.

Alan Stern

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