Hi
On 23.08.2015 09:37, Vincent Pelletier wrote:
Hello,
I have one machine which fails to get a working USB bus on at least
every other boot. This machine having no PS2 ports, bus failure means
no keyboard, and a forced power cycle (sadly, there is no accessible
reset button) to try again.
Do the usb devices work normally after a successful boot?
(no suspicious xhci entries in dmesg)
This is with vanilla kernel as of v4.1.4 tag, but I do not know if this
is a regression (new machine).
Visible USB-related boot messages (boot with "quiet" kernel parameter
to avoid scrolling, messages typed from a screenshot):
[ 7.25] xhci_hcd 0000:00:14.0: Command completion event does not match command
This is not very common, when we queue a command for xhci we write the command to
to the command ring, and also add it to a linked list. We get an event for each completed
command. the event should match the command in the list.
What can I do to debug this issue further ?
Add xhci boot debugging to the kernel cmdline:
dyndbg='module xhci_hcd +p'
or, if as a separate module:
xhci_hcd.dyndbg=+p
Would there be a way to tell the driver to retry when HC dies so I can
at least get the full logs written to disk ? (at a glance, I do not
see one in the source)
Not what I can remember.
If I make some extra xhci debugging patch on top of v4.1.4 can you try it out?
(maybe dumping the command ring and the command list)
-Mathias
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