Re: PROBLEM: kernel hang in ohci init

[David Brownell <david-b@pacbell.net>]

On Thursday 12 July 2007, Satyam Sharma wrote:
> 
> > [2.] The version 2.6.22 of the linux kernel hangs when initializing the
> > integrated ohci controller of the nvidia MCP51 chipset (pci device ids
> > vendor:product == 10de:26d). I have traced through various printks that
> > pci_init calls pci_fixup_device, later on in quirk_usb_ohci_handoff
> > (file linux/drivers/usb/host/pci-quirks.c) kernel freezes in this
> > section:

Note that hangs in that file almost always mean "your BIOS is goofy".
Hunt for BIOS settings related to USB, and change them.  As a rule, if
you tell your BIOS to ignore USB devices (mostly keyboards and disks),
it will have even less of an excuse to break like that.


> > ...
> > if (control & OHCI_CTRL_IR) {
> >         int wait_time = 500;
> >         writel(OHCI_INTR_OC, base + OHCI_INTRENABLE);
> >         writel(OHCI_ORC, base + OHCI_CMDSTATUS); // this never returns
> > ...
> > after this, kernel apparently goes into busy waiting (fans gradually
> > turn louder) and hangs indefinitely. I have also made sure that writel
> > (in linux/include/asm/io.h) really is entered, but never returns.

Does the current kernel.org GIT tree do the same thing?  A bunch
of USB patches were recently merged, including ISTR one in that
area ...


> > I can only guess that it might
> > have to do with the patch
> > "commit 4302a595cd9c6363b495460497ecbda49fa16858
> > Author: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> > Date:   Fri Dec 15 06:53:55 2006 +1100
> > USB: Rework the OHCI quirk mecanism as suggested by David
> > "
> > but I don't really have a clue, so this might be groundless suspicion.

Should be unrelated.  That patch related to how vendor-specific
implementation differences get detected and handled ... basically
just switching to a table-driven approach that can even handle
board-specific wiring braindamage, rather than the original scheme
which was just a big if/then/else looking only at chip vendors.

- Dave
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