On Wed, 17 Jul 2013, Thomas Pugliese wrote:
> Hi,
> What is the expected behavior if a host controller does not implement
> bus_suspend and bus_resume? I am seeing that with the HWA HCD, kworker
> and khubd peg the CPU at 100% because the kernel is constantly calling
> hcd_bus_suspend and hcd_bus_resume. The calls to hcd_bus_suspend and
> hcd_bus_resume fail because hcd->bus_suspend and hcd->bus_resume are NULL.
> I have reproduced this behaviour using 3.11rc1 all the way back to 3.9.2.
I think the expected behavior is close to what you described. :-)
Seriously, AFAIK nobody thought about this case. To prevent this
problem, the HCD's start routine would have to disable runtime PM for
the root hub, by calling
pm_runtime_disable(&hcd->self.root_hub.dev);
Alan Stern
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