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Subject: Re: [PATCH V6 16/21] soc/tegra: pmc: Add pmc wake support for
 tegra210
To:     Sowjanya Komatineni <skomatineni@nvidia.com>,
        thierry.reding@gmail.com, jonathanh@nvidia.com, tglx@linutronix.de,
        jason@lakedaemon.net, marc.zyngier@arm.com,
        linus.walleij@linaro.org, stefan@agner.ch, mark.rutland@arm.com
Cc:     pdeschrijver@nvidia.com, pgaikwad@nvidia.com, sboyd@kernel.org,
        linux-clk@vger.kernel.org, linux-gpio@vger.kernel.org,
        jckuo@nvidia.com, josephl@nvidia.com, talho@nvidia.com,
        linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org,
        mperttunen@nvidia.com, spatra@nvidia.com, robh+dt@kernel.org,
        devicetree@vger.kernel.org
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From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <9848eff6-dc12-850c-25cb-a85a464c0020@gmail.com>
Date:   Wed, 24 Jul 2019 12:31:59 +0300
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24.07.2019 2:39, Sowjanya Komatineni пишет:
> 
> 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@nvidia.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 ..
> 

That's not a bad idea. Wait for one-two weeks and if it will happen that
nobody is replying, then just issue a new version.