[U-Boot] [PATCH 1/3] arm: tegra20: implement early pmic rail configuration

[Stephen Warren]

On 08/20/2015 01:52 AM, Marcel Ziswiler wrote:
> Implement early TPS6586X PMIC rail configuration setting SM0 being
> VDD_CORE_1.2V to 1.2 volts and SM1 being VDD_CPU_1.0V to 1.0 volts.
>
> While those are PMIC power-up defaults the SoC might have been reset
> separately with certain rails being left at lower DVFS states which
> is e.g. the case upon watchdog reset while otherwise nearly idling.

> diff --git a/arch/arm/mach-tegra/tegra20/cpu.c b/arch/arm/mach-tegra/tegra20/cpu.c

>   static void enable_cpu_power_rail(void)
>   {
>   	struct pmc_ctlr *pmc = (struct pmc_ctlr *)NV_PA_PMC_BASE;
>   	u32 reg;
>
> +	debug("%s entry\n", __func__);
> +
> +#ifdef CONFIG_TEGRA_EARLY_TPS6586X
> +	tegra_i2c_ll_init();
> +
> +	/* Set SM0 being VDD_CORE_1.2V to 1.2 volts */
> +	tegra_i2c_ll_write(TPS6586X_SM0V1_REG, 0x13);

Does the CORE rail get adjusted by DVFS? Hopefully if it does, it is 
never set so low that AVP operation at reset is impossible...

> +	udelay(1000);

all the delays in this patch seem very large. What drove the choice of 
the delay values?