linux-kernel - Re: [PATCH v9 20/22] soc/tegra: pmc: Configure deep sleep control settings

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Date:   Mon, 19 Aug 2019 19:48:12 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>,
        thierry.reding@...il.com, jonathanh@...dia.com, tglx@...utronix.de,
        jason@...edaemon.net, marc.zyngier@....com,
        linus.walleij@...aro.org, stefan@...er.ch, mark.rutland@....com
Cc:     pdeschrijver@...dia.com, pgaikwad@...dia.com, sboyd@...nel.org,
        linux-clk@...r.kernel.org, linux-gpio@...r.kernel.org,
        jckuo@...dia.com, josephl@...dia.com, talho@...dia.com,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org,
        mperttunen@...dia.com, spatra@...dia.com, robh+dt@...nel.org,
        devicetree@...r.kernel.org, rjw@...ysocki.net,
        viresh.kumar@...aro.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v9 20/22] soc/tegra: pmc: Configure deep sleep control
 settings

16.08.2019 22:42, 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@...dia.com>
> ---
>  drivers/soc/tegra/pmc.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
> index 53ed70773872..710969043668 100644
> --- a/drivers/soc/tegra/pmc.c
> +++ b/drivers/soc/tegra/pmc.c
> @@ -88,6 +88,8 @@
>  
>  #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
>  
> @@ -2277,7 +2279,7 @@ static const struct tegra_pmc_regs tegra20_pmc_regs = {
>  
>  static void tegra20_pmc_init(struct tegra_pmc *pmc)
>  {
> -	u32 value;
> +	u32 value, osc, pmu, off;
>  
>  	/* Always enable CPU power request */
>  	value = tegra_pmc_readl(pmc, PMC_CNTRL);
> @@ -2303,6 +2305,16 @@ 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);
> +
> +	/* program core timings which are applicable only for suspend state */
> +	if (pmc->suspend_mode != TEGRA_SUSPEND_NONE) {
> +		osc = DIV_ROUND_UP(pmc->core_osc_time * 8192, 1000000);
> +		pmu = DIV_ROUND_UP(pmc->core_pmu_time * 32768, 1000000);
> +		off = DIV_ROUND_UP(pmc->core_off_time * 32768, 1000000);
> +		tegra_pmc_writel(pmc, ((osc << 8) & 0xff00) | (pmu & 0xff),
> +				 PMC_COREPWRGOOD_TIMER);
> +		tegra_pmc_writel(pmc, off, PMC_COREPWROFF_TIMER);
> +	}
>  }
>  
>  static void tegra20_pmc_setup_irq_polarity(struct tegra_pmc *pmc,
> 

In the previous version of this patch there were checks for zero values
of the timers with intention to skip programming of the timers if value
is zero. I'm a bit puzzled by the new version, given that SUSPEND_NONE
means that suspending isn't available at all and thus PMC timers won't
be utilized, hence it shouldn't matter what values are programmed for
the counters, isn't it?