[RFC] [PATCH] ARM: save/restore power control register on Cortex-A9 suspend/resume

[Nicolas Pitre]

On Wed, 2 Jul 2014, Chander Kashyap wrote:

> On Tue, Jul 1, 2014 at 6:18 PM, Russell King - ARM Linux
> <linux at arm.linux.org.uk> wrote:
> > On Tue, Jul 01, 2014 at 06:15:49PM +0530, Chander Kashyap wrote:
> >> The CP15 power register holds clock latency and dynamic clock gating settings
> >> for Cortex-A9 processor, which lost during the suspend/resume. So it needs to
> >> be saved/restored on suspend/resume.
> >>
> >> Signed-off-by: Chander Kashyap <k.chander at samsung.com>
> >> ---
> >>  It is depedent on: ARM: save/restore diagnostic register on Cortex-A9 suspend/resume
> >>  http://www.spinics.net/lists/arm-kernel/msg340506.html
> >>
> >>  arch/arm/mm/proc-v7.S |    6 +++++-
> >>  1 file changed, 5 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
> >> index e26bfaa..9905df5 100644
> >> --- a/arch/arm/mm/proc-v7.S
> >> +++ b/arch/arm/mm/proc-v7.S
> >> @@ -163,12 +163,14 @@ ENDPROC(cpu_v7_do_resume)
> >>       globl_equ       cpu_ca9mp_switch_mm,    cpu_v7_switch_mm
> >>       globl_equ       cpu_ca9mp_set_pte_ext,  cpu_v7_set_pte_ext
> >>  .globl       cpu_ca9mp_suspend_size
> >> -.equ cpu_ca9mp_suspend_size, cpu_v7_suspend_size + 1 * 4
> >> +.equ cpu_ca9mp_suspend_size, cpu_v7_suspend_size + 2 * 4
> >>  #ifdef CONFIG_ARM_CPU_SUSPEND
> >>  ENTRY(cpu_ca9mp_do_suspend)
> >>       stmfd   sp!, {r4}
> >>       mrc     p15, 0, r4, c15, c0, 1  @ Diagnostic register
> >>       stmia   r0!, {r4}
> >> +     mrc     p15, 0, r4, c15, c0, 0  @ Power register
> >> +     stmia   r0!, {r4}
> >>       ldmfd   sp!, {r4}
> >
> > Please combine these - yes, it'll be a larger change, but it'll be much
> > better.
> 
> Are asking me to squash this patch with Shawn's patch?
> If so i will do that.

I'm not sure that's what RMK ment.

You should at least merge the loads and stores into a combined ldmia and 
stmia instructions as illustrated.

> 
> >
> >         stmfd   sp!, {r4-r5}
> >         mrc     p15, 0, r4, c15, c0, 1  @ Diagnostic register
> >         mrc     p15, 0, r5, c15, c0, 0  @ Power register
> >         stmia   r0!, {r4-r5}
> >         ldmfd   sp!, {r4-r5}
> >
> >
> >>       b       cpu_v7_do_suspend
> >>  ENDPROC(cpu_ca9mp_do_suspend)
> >> @@ -176,6 +178,8 @@ ENDPROC(cpu_ca9mp_do_suspend)
> >>  ENTRY(cpu_ca9mp_do_resume)
> >>       ldmia   r0!, {r4}
> >>       mcr     p15, 0, r4, c15, c0, 1  @ Diagnostic register
> >> +     ldmia   r0!, {r4}
> >> +     mcr     p15, 0, r4, c15, c0, 0  @ Power register
> >
> >         ldmia   r0!, {r4-r5}
> >         mcr     p15, 0, r4, c15, c0, 1  @ Diagnostic register
> >         mcr     p15, 0, r5, c15, c0, 0  @ Power register
> 
> I will do these changes
> 
> 
> Thanks for the review.
> 
> >
> >>       b       cpu_v7_do_resume
> >>  ENDPROC(cpu_ca9mp_do_resume)
> >>  #endif
> >
> > Thanks.
> >
> > --
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