On 07/01/2014 11:46 μμ, Sarah Sharp wrote:
On Wed, Dec 25, 2013 at 09:51:28PM -0500, Alan Stern wrote:
Okay, now we know that usb_enable_interface takes a long time. That
routine does nothing but call usb_enable_endpoint, which does nothing
but call usb_hcd_reset_endpoint, which calls the xhci_endpoint_reset
routine.
So we have traced the problem into xhci-hcd. You could trace it
farther down if you want, but at this point it probably would be more
productive to see what Sarah has to say. She may know about some new
changes that are not yet available in the development kernel.
I suspect the patch I asked Matthias and Holger to apply [1] has some
issues, and it's entirely possible that there's deadlocks. One other
tester (Michal) confirms it fixes his issue with a Samsung scanner, but
the patch leads to list corruption in some xHCI structures:
https://bugzilla.kernel.org/show_bug.cgi?id=47421
In any case, all three testers (Matthias, Holger, and Michal) confirm
the patch fixes the underlying issue. So we just need to get the
remaining race conditions and locking issues fixed up.
Xenia, would you mind if Dan or I finished your patch? I know you don't
have much time for xHCI work since you started your new job.
Sarah Sharp
[1] http://marc.info/?l=linux-usb&m=138116117104619&w=2
Yes, sure you can finish the patch.
regards,
xenia
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