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SubjectRe: [PATCH] ARM: mm: cpu_fa526_do_idle: remove WFI
On Mon, Jun 17, 2013 at 04:14:03PM +0200, Arnd Bergmann wrote:
> On Monday 17 June 2013 15:39:20 Jonas Jensen wrote:
> > As it was already suggested by Russell King and Arnd Bergmann ( https://lkml.org/lkml/2013/5/16/133 ), moxart and gemini seem to be the only platforms using CPU_FA526, and instead of pointing arm_pm_idle to an empty function from platform code, it makes sense to remove WFI code from the processor specific idle function.
> >
> > Note: moxart boots and prints to UART without this patch, but input is broken.
>
> Please make sure you have proper line wraps. Lines in checkin
> comments should be no longer than 70 characters normally.
>
> > Signed-off-by: Jonas Jensen <jonas.jensen@gmail.com>
>
> Acked-by: Arnd Bergmann <arnd@arndb.de>
>
> Since this patch is independent from the actual platform support,
> it should go through Russell's patch tracker at
> http://www.arm.linux.org.uk/developer/patches/

Except... the patch is wrong.

> > arch/arm/mm/proc-fa526.S | 4 +---
> > 1 files changed, 1 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/arm/mm/proc-fa526.S b/arch/arm/mm/proc-fa526.S
> > index d217e97..85280b1 100644
> > --- a/arch/arm/mm/proc-fa526.S
> > +++ b/arch/arm/mm/proc-fa526.S
> > @@ -81,9 +81,7 @@ ENDPROC(cpu_fa526_reset)
> > */
> > .align 4
> > ENTRY(cpu_fa526_do_idle)
> > - mcr p15, 0, r0, c7, c0, 4 @ Wait for interrupt
> > - mov pc, lr
> > -
> > + nop

It replaces the WFI and return with a pure nop, so we will fall through
to cpu_fa526_dcache_clean_area(). Do we really want to clean a random
D cache entry depending on what r0 happened to hold at this point? I
think not...


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