Messages in this thread | | | Date | Mon, 15 Oct 2007 16:39:10 -0700 | From | David Brownell <> | Subject | Re: [Linux-usb-users] OHCI root_port_reset() deadly loop... |
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> Bad news, even with the rwsem after a lot more testing I can still > trigger the hang in ohci_hub_control() :-( > > I think we need to go back to considering the total serialization > approach to this problem.
We shouldn't need that. What happens if you add an msleep(5) before ehci-hcd::ehci_run() drops ehci_cf_port_reset_rwsem?
The theory there being that the switch triggered by setting CF doesn't take effect instantaneously, contrary to the effective assumption of that code. A delay of 5 msec seems like it should be more than enough, but that's kind of a guess ... it's good to keep that low, since unfortunately that's in the critical path for OLPC "resume from idle".
- Dave
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