bad pmd

[Matt Reimer]

On Wed, Dec 8, 2010 at 9:02 AM, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
> On Tue, Dec 07, 2010 at 12:26:45PM -0500, Aric D. Blumer wrote:
>> Matt Reimer and I believe we have found what is going on here.  I've put
>> in a fix (no failures yet), but I wanted to bounce it off anyone interested.
>>
>> The PXA platform does not use the "bad pmd" mapping that Russell
>> describes above under normal circumstances, but the PXA resume code
>> (arch/arm/mach-pxa/sleep.S) does on resume:
>
> Good find.
>
>> I'm using the patch below as a fix for now, but it's hard to know what
>> registers are available.  Might be better to just mask it off the lower
>> bits in r1 again.
>>
>>         @ Let us ensure we jump to resume_after_mmu only when the mcr above
>>         @ actually took effect.  They call it the "cpwait" operation.
>> -       mrc     p15, 0, r1, c2, c0, 0           @ queue a dependency on CP15
>> -       sub     pc, r2, r1, lsr #32             @ jump to virtual addr
>> +       mrc     p15, 0, r0, c2, c0, 0           @ queue a dependency on CP15
>> +       sub     pc, r2, r0, lsr #32             @ jump to virtual addr
>
> I don't see anything wrong with this.  Any PXA people want to ack this?

This patch fixes the problem for us. We have yet to see a failure with
this patch applied.

Eric, do you concur that this is a proper fix?

Matt