On Wed, Feb 20, 2013 at 10:54:40AM -0500, Alan Stern wrote: > On Wed, 20 Feb 2013, Tony Camuso wrote: > > > On 02/20/2013 10:15 AM, Alan Stern wrote: > > > On Tue, 19 Feb 2013, Sarah Sharp wrote: > > > > > >> The one thing I wanted to check was my understanding of the hibernate > > >> flow path. As you mentioned, I thought that xhci_suspend would be > > >> called in the hibernate path, but it's not. > > > > > > Are you sure about that? AFAICT it should be called -- although it > > > gets called during the poweroff phase of hibernation, not the freeze > > > phase. > > > > > > core/hcd-pci.c: usb_hcd_pci_pm_ops.poweroff = hcd_pci_suspend > > > core/hcd-pci.c: hcd_pci_suspend calls suspend_common > > > core/hcd-pci.c: suspend_common calls hcd->driver->pci_suspend > > > host/xhci-pci.c: xhci_pci_hc_driver.pci_suspend = xhci_pci_suspend > > > host/xhci-pci.c: xhci_pci_suspend calls xhci_suspend > > > > > We instrumented the code, and when invoking pm-hibernate, we did > > not flow through xhci_suspend(), where the timer is deleted. > > If you instrumented the code then you ought to know how the actual > behavior differs from what I outlined above. Where is the difference? Hi Alan, I worked with Tony on this issue. The instrumentation we did was to add printks in the xhci_suspend, xhci_resume and compliance_mode_recovery_timer_init. What we noticed was that the xhci_suspend was not called during hibernate. As a result the timer was not deleted. During the resume, xhci_init called compliance_mode_recovery_timer_init which caused the initial panic (adding an existing timer). We added code to compliance_mode_recovery_timer_init to bail if the timer was already enabled. This lead us to the second problem at the bottom of xhci_resume where compliance_mode_recovery_timer_init was called again. We did not attempt to understand the mechanics of how suspend/hibernate and resume worked. We just assumed based on the hibernate flag to xhci_resume there were two code paths. If the expectation is that xhci_suspend should be called during hibernate, I can work with Tony to figure out why this is not happening. Solving that problem would partially solve our problem. We would still need the !hibernate flag at the bottom of xhci_resume to surround the timer check to deal with xhci_init calling the same init function. Cheers, Don -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
