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

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Date:   Mon, 19 Aug 2019 11:20:21 -0700
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Dmitry Osipenko <digetx@...il.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


On 8/19/19 9:48 AM, Dmitry Osipenko wrote:
> 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?

Yes, as I see in documentation we already specify all these timings are 
required properties when suspend mode is used, I updated in this version 
to program core timings only when suspend mode is enabled.