[PATCH] ARM: save/restore diagnostic register on ARMv7 suspend/resume

[Russell King - ARM Linux]

On Wed, Jun 18, 2014 at 08:39:08PM +0800, Shawn Guo wrote:
> On Wed, Jun 18, 2014 at 11:40:09AM +0100, Will Deacon wrote:
> > On Wed, Jun 18, 2014 at 09:49:58AM +0100, Shawn Guo wrote:
> > > The CP15 diagnostic register holds ARM errata bits on ARMv7, so it
> > > needs to be saved/restored on suspend/resume.  Otherwise, the
> > > effectiveness of errata workaround gets lost together with diagnostic
> > > register bit across suspend/resume cycle.
> > 
> > This should be conditional on Cortex-A9, since this register is certainly
> > not architected.
> 
> Ah, yes.  In that case, I should probably handle it at platform level to
> avoid messing up generic ARMv7 suspend/resume routines.

We don't need more platform code repeating this kind of stuff...

All Cortex-A9 which have these work-arounds enabled may need this and
as the generic kernel already fiddles with this, it's something that
should not be platform specific - indeed, some of these workarounds
are supposed to be in place before the MMU is enabled.

So, it's being done at the preferred place in the kernel... just not
in a way that results in only Cortex A9 being affected.

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