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

Dmitry Osipenko
2019-06-29T13:00:05Z

28.06.2019 5:12, Sowjanya Komatineni пишет:
> 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@nvidia.com>
> ---
> 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?