Re: [PATCH V5 16/18] soc/tegra: pmc: Configure deep sleep control settings

[Dmitry Osipenko]

28.06.2019 5:12, Sowjanya Komatineni ÐÐÑÐÑ:
> Tegra210 and prior Tegra chips have deep sleep entry and wakeup related
> timings which are platform specific that should be configured before
> entering into deep sleep.
> 
> Below are the timing specific configurations for deep sleep entry and
> wakeup.
> - Core rail power-on stabilization timer
> - OSC clock stabilization timer after SOC rail power is stabilized.
> - Core power off time is the minimum wake delay to keep the system
>   in deep sleep state irrespective of any quick wake event.
> 
> These values depends on the discharge time of regulators and turn OFF
> time of the PMIC to allow the complete system to finish entering into
> deep sleep state.
> 
> These values vary based on the platform design and are specified
> through the device tree.
> 
> This patch has implementation to configure these timings which are must
> to have for proper deep sleep and wakeup operations.
> 
> Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
> ---
>  drivers/soc/tegra/pmc.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
> index ed83c0cd09a3..7e4a8f04f4c4 100644
> --- a/drivers/soc/tegra/pmc.c
> +++ b/drivers/soc/tegra/pmc.c
> @@ -89,6 +89,8 @@
>  
>  #define PMC_CPUPWRGOOD_TIMER		0xc8
>  #define PMC_CPUPWROFF_TIMER		0xcc
> +#define PMC_COREPWRGOOD_TIMER		0x3c
> +#define PMC_COREPWROFF_TIMER		0xe0
>  
>  #define PMC_PWR_DET_VALUE		0xe4
>  
> @@ -2291,6 +2293,7 @@ static const struct tegra_pmc_regs tegra20_pmc_regs = {
>  static void tegra20_pmc_init(struct tegra_pmc *pmc)
>  {
>  	u32 value;
> +	unsigned long osc, pmu, off;
>  
>  	/* Always enable CPU power request */
>  	value = tegra_pmc_readl(pmc, PMC_CNTRL);
> @@ -2316,6 +2319,15 @@ static void tegra20_pmc_init(struct tegra_pmc *pmc)
>  	value = tegra_pmc_readl(pmc, PMC_CNTRL);
>  	value |= PMC_CNTRL_SYSCLK_OE;
>  	tegra_pmc_writel(pmc, value, PMC_CNTRL);
> +
> +	osc = DIV_ROUND_UP_ULL(pmc->core_osc_time * 8192, 1000000);
> +	pmu = DIV_ROUND_UP_ULL(pmc->core_pmu_time * 32768, 1000000);
> +	off = DIV_ROUND_UP_ULL(pmc->core_off_time * 32768, 1000000);

IIUC, the first argument shall be explicitly of a type "long long", shouldn't it?
Otherwise the multiplication will overflow before division happens.

Thus:

	osc = DIV_ROUND_UP_ULL((u64)pmc->core_osc_time * 8192, 1000000);
	pmu = DIV_ROUND_UP_ULL((u64)pmc->core_pmu_time * 32768, 1000000);
	off = DIV_ROUND_UP_ULL((u64)pmc->core_off_time * 32768, 1000000);

Also, could you please tell what of the above multiplications could overflow u32 in
the first place? Maybe DIV_ROUND_UP_ULL isn't needed at all and DIV_ROUND_UP could be
use instead?