Re: Oops in UHCI when encountering "host controller process error"

From: Jeremy Fitzhardinge
Date: Fri Oct 17 2008 - 11:20:57 EST

Alan Stern wrote:
------------[ cut here ]------------
WARNING: at /home/jeremy/hg/xen/paravirt/linux/drivers/usb/host/uhci-q.c:1744 uhci_scan_schedule+0xb7/0x9a3()
uhci->skelqh[1]-> is NULL

Odd. Is skelqh[1] the only entry whose is NULL? Not skelqh[2] or others?

No, the others too, but all the WARN_ON backtraces got very verbose and I had to rush home at the end of the day.

The node is initialized during uhci_start() in uhci-hcd.c -- there's a
loop which initializes all the uhci->skelqh[i] entries by calling
uhci_alloc_qh(). You should check inside that loop to see whether
uhci->skelqh[i]-> is NULL to begin with. If it is then
something about the DMA-coherent memory is funny; if not then the
linked list pointer gets corrupted somewhere.

OK, will check it out.

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