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

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Date:   Mon, 19 Aug 2019 12:07:50 -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 11:20 AM, Sowjanya Komatineni wrote:
>
> 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.
>
In other words, core timings are for SC7 entry only. So when SC7/suspend 
mode is not used, these timings doesn't matter.