[PATCH 07/17] omap4: pm: CPU1 wakeup workaround form Low power modes

[Kevin Hilman]

Santosh Shilimkar <santosh.shilimkar at ti.com> writes:

> The SGI(Software Generated Interrupts) are not wakeup capable from
> low power states. This is known limitation on OMAP4 and needs to be
> worked around by using software forced clockdomain wake-up. CPU0 forces
> the CPU1 clockdomain to software force wakeup. After the wakeup, CPU1
> restores its clockdomain hardware supervised mode.
>
> More details can be found in OMAP4430 TRM - Version J
> Section :
> 	4.3.4.2 Power States of CPU0 and CPU1
>
> Signed-off-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
> Reviewed-by: Kevin Hilman <khilman at ti.com>
> ---
>  arch/arm/mach-omap2/omap-hotplug.c |    9 +++++++++
>  arch/arm/mach-omap2/omap-smp.c     |   27 ++++++++++++++++++++++++++-
>  2 files changed, 35 insertions(+), 1 deletions(-)
>
> diff --git a/arch/arm/mach-omap2/omap-hotplug.c b/arch/arm/mach-omap2/omap-hotplug.c
> index 9f8f097..cf4ab15 100644
> --- a/arch/arm/mach-omap2/omap-hotplug.c
> +++ b/arch/arm/mach-omap2/omap-hotplug.c
> @@ -23,6 +23,7 @@
>  #include <mach/omap-wakeupgen.h>
>  
>  #include "powerdomain.h"
> +#include "clockdomain.h"
>  
>  int platform_cpu_kill(unsigned int cpu)
>  {
> @@ -36,6 +37,11 @@ int platform_cpu_kill(unsigned int cpu)
>  void platform_cpu_die(unsigned int cpu)
>  {
>  	unsigned int this_cpu;
> +	static struct clockdomain *cpu1_clkdm;
> +
> +	/* To avoid cpu1 clockdomain lookup every time */

minor: comment doesn't really match code and could just be removed

> +	if (!cpu1_clkdm)
> +		cpu1_clkdm = clkdm_lookup("mpu1_clkdm");
>  
>  	flush_cache_all();
>  	dsb();
> @@ -59,6 +65,9 @@ void platform_cpu_die(unsigned int cpu)
>  			 * OK, proper wakeup, we're done
>  			 */
>  			omap_wakeupgen_irqmask_all(this_cpu, 0);
> +
> +			/* Restore clockdomain to hardware supervised */
> +			clkdm_allow_idle(cpu1_clkdm);
>  			break;
>  		}
>  		pr_debug("CPU%u: spurious wakeup call\n", cpu);
> diff --git a/arch/arm/mach-omap2/omap-smp.c b/arch/arm/mach-omap2/omap-smp.c
> index b105a29..31c9b79 100644
> --- a/arch/arm/mach-omap2/omap-smp.c
> +++ b/arch/arm/mach-omap2/omap-smp.c
> @@ -25,6 +25,8 @@
>  #include <mach/hardware.h>
>  #include <mach/omap4-common.h>
>  
> +#include "clockdomain.h"
> +
>  /* SCU base address */
>  void __iomem *scu_base;
>  
> @@ -48,6 +50,8 @@ void __cpuinit platform_secondary_init(unsigned int cpu)
>  
>  int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
>  {
> +	static struct clockdomain *cpu1_clkdm;
> +	static bool booted;
>  	/*
>  	 * Set synchronisation state between this boot processor
>  	 * and the secondary one
> @@ -63,7 +67,28 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
>  	omap_modify_auxcoreboot0(0x200, 0xfffffdff);
>  	flush_cache_all();
>  	smp_wmb();
> -	smp_cross_call(cpumask_of(cpu), 1);
> +
> +	/* To avoid cpu1 clockdomain lookup every time */

ditto

> +	if (!cpu1_clkdm)
> +		cpu1_clkdm = clkdm_lookup("mpu1_clkdm");
> +
> +	/*
> +	 * The SGI(Software Generated Interrupts) are not wakeup capable
> +	 * from low power states. This is known limitation on OMAP4 and
> +	 * needs to be worked around by using software forced clockdomain
> +	 * wake-up. To wakeup CPU1, CPU0 forces the CPU1 clockdomain to
> +	 * software force wakeup. After the wakeup, CPU1 restores its
> +	 * clockdomain hardware supervised mode.
> +	 * More details can be found in OMAP4430 TRM - Version J
> +	 * Section :
> +	 *	4.3.4.2 Power States of CPU0 and CPU1
> +	 */
> +	if (booted) {
> +		clkdm_wakeup(cpu1_clkdm);
> +	} else {
> +		dsb_sev();
> +		booted = true;
> +	}
>  
>  	/*
>  	 * Now the secondary core is starting up let it run its