Re: [PATCH V4 4/9] ARM: tegra: pm: add platform suspend support

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 03/18/2013 02:13 AM, Joseph Lo wrote:
> Adding suspend to RAM support for Tegra platform. There are three suspend
> mode for Tegra. The difference were below.
> 
> * LP2: CPU voltage off
> * LP1: CPU voltage off, DRAM in self-refresh
> * LP0: CPU + Core voltage off, DRAM in self-refresh
> 
> After this patch, the LP2 suspend mode will be supported.

> diff --git a/arch/arm/mach-tegra/common.c b/arch/arm/mach-tegra/common.c
> index c84505c..024f355 100644
> --- a/arch/arm/mach-tegra/common.c
> +++ b/arch/arm/mach-tegra/common.c
> @@ -66,6 +66,7 @@ void __init tegra_dt_init_irq(void)
>  	tegra_init_irq();
>  	irqchip_init();
>  	tegra_legacy_irq_syscore_init();
> +	tegra_init_suspend();

Does that have to be part of tegra_dt_init_irq()? Can't we initialize
suspend support in some later hook. init_irq() should just initialize IRQs.

> diff --git a/arch/arm/mach-tegra/pmc.c b/arch/arm/mach-tegra/pmc.c

> -void set_power_timers(unsigned long us_on, unsigned long us_off)
> +static void set_power_timers(u32 us_on, u32 us_off, unsigned long rate)
>  {
>  	unsigned long long ticks;
>  	unsigned long long pclk;
> -	unsigned long rate;
>  	static unsigned long tegra_last_pclk;
>  
> -	rate = clk_get_rate(tegra_pclk);
> -
>  	if (WARN_ON_ONCE(rate <= 0))
>  		pclk = 100000000;
>  	else

I don't think the code compiles after that?

The code must both compile and execute correctly after each patch is
applied, without relying on any future patches.

> +void tegra_pmc_pm_set(enum tegra_suspend_mode mode)
> +{
> +	u32 reg;
> +	unsigned long rate = 0;
> +
> +	reg = tegra_pmc_readl(PMC_CTRL);
> +	reg |= TEGRA_POWER_CPU_PWRREQ_OE;
> +	reg &= ~TEGRA_POWER_EFFECT_LP0;
> +
> +	switch (mode) {
> +	case TEGRA_SUSPEND_LP2:
> +		rate = clk_get_rate(tegra_pclk);

That isn't used anywhere.

> +void tegra_pmc_suspend_init(void)
> +{
> +	u32 reg;
> +
> +	/* Always enable CPU power request; just normal polarity is supported */
> +	reg = tegra_pmc_readl(PMC_CTRL);
> +	BUG_ON(reg & TEGRA_POWER_CPU_PWRREQ_POLARITY);

Why is that comment true? What does it take to support arbitrary
polarity; just flipping the OE bit in the register?