[PATCHv2 17/19] ARM: OMAP4: put cpu1 back to sleep if no wake request

[Tero Kristo]

On Wed, 2012-05-16 at 17:31 -0700, Kevin Hilman wrote:
> Tero Kristo <t-kristo at ti.com> writes:
> 
> > If AUX_CORE_BOOT0 does not indicate wakeup request for cpu1, put it back
> > to off. 
> 
> Why is it waking up then?  (I know the answer, but will forget.  The
> changelog serves as my long-term memory.)

Will add comment. (Both cpus will wake-up after device-off reset.)

> 
> > This is needed during wakeup from device off to prevent cpu1
> > from being stuck indefinitely in the wakeup loop 
> 
> Why does it get stuck?

Related to the above, if the AUX_CORE_BOOT0 is not set, the code will
wait for it indefinitely in busy loop.

> 
> > and also to prevent wakeup problem on GP chips with device off mode.
> 
> What wakeup problem?

This is apparently related to the GIC restore issue addressed with patch
3/8 of the core-ret set (workaround for the ROM bug because of CA9 r2pX
gic register change), the interrupts get disabled. Maybe Santosh has
some comments on this one.
> 
> > Signed-off-by: Tero Kristo <t-kristo at ti.com>
> 
> Assembly code should have some comments to aid comprehension.

Will add.

> 
> 
> > ---
> >  arch/arm/mach-omap2/omap-headsmp.S |   45 ++++++++++++++++++++++++++++++++---
> >  1 files changed, 41 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/arm/mach-omap2/omap-headsmp.S b/arch/arm/mach-omap2/omap-headsmp.S
> > index d602555..59c6578 100644
> > --- a/arch/arm/mach-omap2/omap-headsmp.S
> > +++ b/arch/arm/mach-omap2/omap-headsmp.S
> > @@ -17,8 +17,37 @@
> >  
> >  #include <linux/linkage.h>
> >  #include <linux/init.h>
> > +#include <mach/omap-secure.h>
> > +#include "prcm_mpu44xx.h"
> > +
> > +#define CPU1_PWRSTCTRL (OMAP4430_PRCM_MPU_BASE + OMAP4430_PRCM_MPU_CPU1_INST + \
> > +			OMAP4_PM_CPU1_PWRSTCTRL_OFFSET)
> >  
> >  	__CPUINIT
> > +
> > +ENTRY(omap_cpu1_off)
> > +	ldr	r12, =CPU1_PWRSTCTRL
> > +	ldr	r0, [r12]
> > +	and	r0, #3
> > +	cmp	r0, #2
> > +	beq	exit_cpu1_off
> > +
> > +	mov	r0, #0x3
> > +	mov	r1, #0x0
> > +	ldr	r12, =OMAP4_MON_SCU_PWR_INDEX
> 
> Help!  no comments.
> 
> > +	dsb
> > +	smc     #0
> 
> The DO_SMC in sleep44xx.S suggests there should be another dsb here.

Not sure if that is needed here as we have multiple barriers following
this, but I'll add it just to be sure.

> 
> > +	isb
> > +	dsb
> > +	dmb
> > +	wfi
> > +	nop
> > +	nop
> 
> Shoudln't this use omap_do_wfi?

Can't, as we don't have stack yet at this point, and omap_do_wfi
attempts to push stuff into stack.

-Tero

> 
> Kevin
> 
> > +exit_cpu1_off:
> > +	mov	pc, lr
> > +ENDPROC(omap_cpu1_off)
> > +
> >  /*
> >   * OMAP4 specific entry point for secondary CPU to jump from ROM
> >   * code.  This routine also provides a holding flag into which
> > @@ -27,32 +56,40 @@
> >   * register AuxCoreBoot0.
> >   */
> >  ENTRY(omap_secondary_startup)
> > -hold:	ldr	r12,=0x103
> > +	ldr	r12,=0x103
> >  	dsb
> >  	smc	#0			@ read from AuxCoreBoot0
> >  	mov	r0, r0, lsr #9
> >  	mrc	p15, 0, r4, c0, c0, 5
> >  	and	r4, r4, #0x0f
> >  	cmp	r0, r4
> > -	bne	hold
> > +	beq	omap_cont_boot
> > +
> > +	bl	omap_cpu1_off
> > +	b	omap_secondary_startup
> >  
> >  	/*
> >  	 * we've been released from the wait loop,secondary_stack
> >  	 * should now contain the SVC stack for this core
> >  	 */
> > +omap_cont_boot:
> >  	b	secondary_startup
> >  ENDPROC(omap_secondary_startup)
> >  
> >  ENTRY(omap_secondary_startup_4460)
> > -hold_2:	ldr	r12,=0x103
> > +	ldr	r12,=0x103
> >  	dsb
> >  	smc	#0			@ read from AuxCoreBoot0
> >  	mov	r0, r0, lsr #9
> >  	mrc	p15, 0, r4, c0, c0, 5
> >  	and	r4, r4, #0x0f
> >  	cmp	r0, r4
> > -	bne	hold_2
> > +	beq	omap4460_cont_boot
> > +
> > +	bl	omap_cpu1_off
> > +	b	omap_secondary_startup_4460
> >  
> > +omap4460_cont_boot:
> >  	/*
> >  	 * GIC distributor control register has changed between
> >  	 * CortexA9 r1pX and r2pX. The Control Register secure