On 22.11.2016 11:52, Simon Arlott wrote:
On 22/11/16 08:37, Mathias Nyman wrote:
On 21.11.2016 23:52, Simon Arlott wrote:
2016-06-17T09:56:09.219+01:00 <warning> kernel: xhci_hcd 0000:00:14.0: URB transfer length is wrong, xHC issue? req. len = 4, act. len = 4294967292
Your broken hardware triggered another interesting issue.
The len value 4294967292 looks like a u32 wrapped around.
What kernelversion was this?
These versions:
1 Linux version 4.4.0-24-generic (buildd@lgw01-12) (gcc version 5.3.1 20160413 (Ubuntu 5.3.1-14ubuntu2.1) ) #43-Ubuntu SMP Wed Jun 8 19:27:37 UTC 2016 (Ubuntu 4.4.0-24.43-generic 4.4.10)
134694 xhci_hcd 0000:00:14.0: URB transfer length is wrong, xHC issue? req. len = 4, act. len = 4294967292
Ok, there are no fixes in the control transfers pde since 4.4-0-24, so whatever is causing this is still there.
Probably related to how we calculate the length of these erronous control transfers.
one clear fault is that we overwrite the previous error code with a zero if the length mismatch.
Can you take a log with xhci debugging enabled, this can be done by:
echo -n 'module xhci_hcd =p' > /sys/kernel/debug/dynamic_debug/control
before plugging in the faulty hub (cable)
A usbmon trace would also help, see Documentation/usb/usbmon.txt
How about If I write some test patches, do you have the time to apply them and try them out?
-Mathias
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