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Subject: Re: PROBLEM: memory corrupting bug, bisected to 6dda9d55
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Segher Boessenkool <segher@kernel.crashing.org>
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Date: Wed, 20 Oct 2010 08:02:48 +1100
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On Tue, 2010-10-19 at 22:47 +0200, Segher Boessenkool wrote:
> 
> It looks like it is the frame counter in an USB OHCI HCCA.
> 16-bit, 1kHz update, offset x'80 in a page.
> 
> So either the kernel forgot to call quiesce on it, or the firmware
> doesn't implement that, or the firmware messed up some other way.

I vote for the FW being on crack. Wouldn't be the first time with
Pegasos.

It's an OHCI or an UHCI in there ?

Can you try in prom_init.c changing the prom_close_stdin() function to
also close "stdout" ? 

         if (prom_getprop(_prom->chosen, "stdin", &val, sizeof(val)) > 0)
                 call_prom("close", 1, 0, val);
+        if (prom_getprop(_prom->chosen, "stdout", &val, sizeof(val)) > 0)
+               call_prom("close", 1, 0, val);

See if that makes a difference ?

Last option would be to manually turn the thing off with MMIO in yet-another
pegasos workaround in prom_init.c.

Cheers,
Ben.