Date:   Tue, 23 Jul 2019 16:39:48 -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>
Subject: Re: [PATCH V6 16/21] soc/tegra: pmc: Add pmc wake support for
 tegra210


On 7/23/19 7:27 AM, Dmitry Osipenko wrote:
> 23.07.2019 6:43, Dmitry Osipenko пишет:
>> 23.07.2019 6:31, Sowjanya Komatineni пишет:
>>> On 7/22/19 8:25 PM, Dmitry Osipenko wrote:
>>>> 23.07.2019 6:09, Sowjanya Komatineni пишет:
>>>>> On 7/22/19 8:03 PM, Dmitry Osipenko wrote:
>>>>>> 23.07.2019 4:52, Sowjanya Komatineni пишет:
>>>>>>> On 7/22/19 6:41 PM, Dmitry Osipenko wrote:
>>>>>>>> 23.07.2019 4:08, Dmitry Osipenko пишет:
>>>>>>>>> 23.07.2019 3:58, Dmitry Osipenko пишет:
>>>>>>>>>> 21.07.2019 22:40, Sowjanya Komatineni пишет:
>>>>>>>>>>> This patch implements PMC wakeup sequence for Tegra210 and defines
>>>>>>>>>>> common used RTC alarm wake event.
>>>>>>>>>>>
>>>>>>>>>>> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
>>>>>>>>>>> ---
>>>>>>>>>>>     drivers/soc/tegra/pmc.c | 111
>>>>>>>>>>> ++++++++++++++++++++++++++++++++++++++++++++++++
>>>>>>>>>>>     1 file changed, 111 insertions(+)
>>>>>>>>>>>
>>>>>>>>>>> diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
>>>>>>>>>>> index 91c84d0e66ae..c556f38874e1 100644
>>>>>>>>>>> --- a/drivers/soc/tegra/pmc.c
>>>>>>>>>>> +++ b/drivers/soc/tegra/pmc.c
>>>>>>>>>>> @@ -57,6 +57,12 @@
>>>>>>>>>>>     #define  PMC_CNTRL_SYSCLK_OE        BIT(11) /* system clock
>>>>>>>>>>> enable */
>>>>>>>>>>>     #define  PMC_CNTRL_SYSCLK_POLARITY    BIT(10) /* sys clk
>>>>>>>>>>> polarity */
>>>>>>>>>>>     #define  PMC_CNTRL_MAIN_RST        BIT(4)
>>>>>>>>>>> +#define  PMC_CNTRL_LATCH_WAKEUPS    BIT(5)
>>>>>>>>> Please follow the TRM's bits naming.
>>>>>>>>>
>>>>>>>>> PMC_CNTRL_LATCHWAKE_EN
>>>>>>>>>
>>>>>>>>>>> +#define PMC_WAKE_MASK            0x0c
>>>>>>>>>>> +#define PMC_WAKE_LEVEL            0x10
>>>>>>>>>>> +#define PMC_WAKE_STATUS            0x14
>>>>>>>>>>> +#define PMC_SW_WAKE_STATUS        0x18
>>>>>>>>>>>       #define DPD_SAMPLE            0x020
>>>>>>>>>>>     #define  DPD_SAMPLE_ENABLE        BIT(0)
>>>>>>>>>>> @@ -87,6 +93,11 @@
>>>>>>>>>>>       #define PMC_SCRATCH41            0x140
>>>>>>>>>>>     +#define PMC_WAKE2_MASK            0x160
>>>>>>>>>>> +#define PMC_WAKE2_LEVEL            0x164
>>>>>>>>>>> +#define PMC_WAKE2_STATUS        0x168
>>>>>>>>>>> +#define PMC_SW_WAKE2_STATUS        0x16c
>>>>>>>>>>> +
>>>>>>>>>>>     #define PMC_SENSOR_CTRL            0x1b0
>>>>>>>>>>>     #define  PMC_SENSOR_CTRL_SCRATCH_WRITE    BIT(2)
>>>>>>>>>>>     #define  PMC_SENSOR_CTRL_ENABLE_RST    BIT(1)
>>>>>>>>>>> @@ -1922,6 +1933,55 @@ static const struct irq_domain_ops
>>>>>>>>>>> tegra_pmc_irq_domain_ops = {
>>>>>>>>>>>         .alloc = tegra_pmc_irq_alloc,
>>>>>>>>>>>     };
>>>>>>>>>>>     +static int tegra210_pmc_irq_set_wake(struct irq_data *data,
>>>>>>>>>>> unsigned int on)
>>>>>>>>>>> +{
>>>>>>>>>>> +    struct tegra_pmc *pmc = irq_data_get_irq_chip_data(data);
>>>>>>>>>>> +    unsigned int offset, bit;
>>>>>>>>>>> +    u32 value;
>>>>>>>>>>> +
>>>>>>>>>>> +    if (data->hwirq == ULONG_MAX)
>>>>>>>>>>> +        return 0;
>>>>>>>>>>> +
>>>>>>>>>>> +    offset = data->hwirq / 32;
>>>>>>>>>>> +    bit = data->hwirq % 32;
>>>>>>>>>>> +
>>>>>>>>>>> +    /*
>>>>>>>>>>> +     * Latch wakeups to SW_WAKE_STATUS register to capture events
>>>>>>>>>>> +     * that would not make it into wakeup event register during
>>>>>>>>>>> LP0 exit.
>>>>>>>>>>> +     */
>>>>>>>>>>> +    value = tegra_pmc_readl(pmc, PMC_CNTRL);
>>>>>>>>>>> +    value |= PMC_CNTRL_LATCH_WAKEUPS;
>>>>>>>>>>> +    tegra_pmc_writel(pmc, value, PMC_CNTRL);
>>>>>>>>>>> +    udelay(120);
>>>>>>>>>> Why it takes so much time to latch the values? Shouldn't some
>>>>>>>>>> status-bit
>>>>>>>>>> be polled for the completion of latching?
>>>>>>>>>>
>>>>>>>>>> Is this register-write really getting buffered in the PMC?
>>>>>>>>>>
>>>>>>>>>>> +    value &= ~PMC_CNTRL_LATCH_WAKEUPS;
>>>>>>>>>>> +    tegra_pmc_writel(pmc, value, PMC_CNTRL);
>>>>>>>>>>> +    udelay(120);
>>>>>>>>>> 120 usecs to remove latching, really?
>>>>>>>>>>
>>>>>>>>>>> +    tegra_pmc_writel(pmc, 0, PMC_SW_WAKE_STATUS);
>>>>>>>>>>> +    tegra_pmc_writel(pmc, 0, PMC_SW_WAKE2_STATUS);
>>>>>>>>>>> +
>>>>>>>>>>> +    tegra_pmc_writel(pmc, 0, PMC_WAKE_STATUS);
>>>>>>>>>>> +    tegra_pmc_writel(pmc, 0, PMC_WAKE2_STATUS);
>>>>>>>>>>> +
>>>>>>>>>>> +    /* enable PMC wake */
>>>>>>>>>>> +    if (data->hwirq >= 32)
>>>>>>>>>>> +        offset = PMC_WAKE2_MASK;
>>>>>>>>>>> +    else
>>>>>>>>>>> +        offset = PMC_WAKE_MASK;
>>>>>>>>>>> +
>>>>>>>>>>> +    value = tegra_pmc_readl(pmc, offset);
>>>>>>>>>>> +
>>>>>>>>>>> +    if (on)
>>>>>>>>>>> +        value |= 1 << bit;
>>>>>>>>>>> +    else
>>>>>>>>>>> +        value &= ~(1 << bit);
>>>>>>>>>>> +
>>>>>>>>>>> +    tegra_pmc_writel(pmc, value, offset);
>>>>>>>>>> Why the latching is done *before* writing into the WAKE registers?
>>>>>>>>>> What
>>>>>>>>>> it is latching then?
>>>>>>>>> I'm looking at the TRM doc and it says that latching should be done
>>>>>>>>> *after* writing to the WAKE_MASK / LEVEL registers.
>>>>>>>>>
>>>>>>>>> Secondly it says that it's enough to do:
>>>>>>>>>
>>>>>>>>> value = tegra_pmc_readl(pmc, PMC_CNTRL);
>>>>>>>>> value |= PMC_CNTRL_LATCH_WAKEUPS;
>>>>>>>>> tegra_pmc_writel(pmc, value, PMC_CNTRL);
>>>>>>>>>
>>>>>>>>> in order to latch. There is no need for the delay and to remove the
>>>>>>>>> "LATCHWAKE_EN" bit, it should be a oneshot action.
>>>>>>>> Although, no. TRM says "stops latching on transition from 1
>>>>>>>> to 0 (sequence - set to 1,set to 0)", so it's not a oneshot action.
>>>>>>>>
>>>>>>>> Have you tested this code at all? I'm wondering how it happens to
>>>>>>>> work
>>>>>>>> without a proper latching.
>>>>>>> Yes, ofcourse its tested and this sequence to do transition is
>>>>>>> recommendation from Tegra designer.
>>>>>>> Will check if TRM doesn't have update properly or will re-confirm
>>>>>>> internally on delay time...
>>>>>>>
>>>>>>> On any of the wake event PMC wakeup happens and WAKE_STATUS register
>>>>>>> will have bits set for all events that triggered wake.
>>>>>>> After wakeup PMC doesn't update SW_WAKE_STATUS register as per PMC
>>>>>>> design.
>>>>>>> SW latch register added in design helps to provide a way to capture
>>>>>>> those events that happen right during wakeup time and didnt make it to
>>>>>>> SW_WAKE_STATUS register.
>>>>>>> So before next suspend entry, latching all prior wake events into SW
>>>>>>> WAKE_STATUS and then clearing them.
>>>>>> I'm now wondering whether the latching cold be turned ON permanently
>>>>>> during of the PMC's probe, for simplicity.
>>>>> latching should be done on suspend-resume cycle as wake events gets
>>>>> generates on every suspend-resume cycle.
>>>> You're saying that PMC "doesn't update SW_WAKE_STATUS" after wake-up,
>>>> then I don't quite understand what's the point of disabling the latching
>>>> at all.
>>> When latch wake enable is set, events are latched and during 1 to 0
>>> transition latching is disabled.
>>>
>>> This is to avoid sw_wake_status and wake_status showing diff events.
>> Okay.
>>
>>> Currently driver is not relying on SW_WAKE_STATUS but its good to latch
>>> and clear so even at some point for some reason when SW_WAKE_STATUS is
>>> used, this wlil not cause mismatch with wake_status.
>> Then the latching need to be enabled on suspend and disabled early on
>> resume to get a proper WAKE status.
> Actually, it will be better to simply not implement the latching until
> it will become really needed. In general you shouldn't add into the
> patchset anything that is unused.

OK, will remove latch_wake for now.

Will send next version once I get all the review feedback ..

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