Re: [PATCH V6 16/21] soc/tegra: pmc: Add pmc wake support for tegra210

From: Sowjanya Komatineni <skomatineni@nvidia.com>
To: Dmitry Osipenko <digetx@gmail.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>
Subject: Re: [PATCH V6 16/21] soc/tegra: pmc: Add pmc wake support for tegra210
Date: Mon, 22 Jul 2019 20:31:02 -0700	[thread overview]
Message-ID: <97096b6c-f2f5-b82a-b172-802f4a06d1af@nvidia.com> (raw)
In-Reply-To: <71c8cab1-bf72-c073-be30-4263c6b7c871@gmail.com>

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.

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.

>>>> LATCHWAKE_EN - When set, enables latching and stops latching on
>>>> transition from 1 to 0
>>>> There is recommendation of min 120uSec for this transition to stop
>>>> latching. Will double-check why 120uSec
>>> Yes, please check.
>>>
>>>>>>>> +    return 0;
>>>>>>>> +}
>>>>>>>> +
>>>>>>>>    static int tegra186_pmc_irq_set_wake(struct irq_data *data,
>>>>>>>> unsigned int on)
>>>>>>>>    {
>>>>>>>>        struct tegra_pmc *pmc = irq_data_get_irq_chip_data(data);
>>>>>>>> @@ -1954,6 +2014,49 @@ static int
>>>>>>>> tegra186_pmc_irq_set_wake(struct irq_data *data, unsigned int on)
>>>>>>>>        return 0;
>>>>>>>>    }
>>>>>>>>    +static int tegra210_pmc_irq_set_type(struct irq_data *data,
>>>>>>>> unsigned int type)
>>>>>>>> +{
>>>>>>>> +    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;
>>>>>>>> +
>>>>>>>> +    if (data->hwirq >= 32)
>>>>>>>> +        offset = PMC_WAKE2_LEVEL;
>>>>>>>> +    else
>>>>>>>> +        offset = PMC_WAKE_LEVEL;
>>>>>>>> +
>>>>>>>> +    value = tegra_pmc_readl(pmc, offset);
>>>>>>>> +
>>>>>>>> +    switch (type) {
>>>>>>>> +    case IRQ_TYPE_EDGE_RISING:
>>>>>>>> +    case IRQ_TYPE_LEVEL_HIGH:
>>>>>>>> +        value |= 1 << bit;
>>>>>>>> +        break;
>>>>>>>> +
>>>>>>>> +    case IRQ_TYPE_EDGE_FALLING:
>>>>>>>> +    case IRQ_TYPE_LEVEL_LOW:
>>>>>>>> +        value &= ~(1 << bit);
>>>>>>>> +        break;
>>>>>>>> +
>>>>>>>> +    case IRQ_TYPE_EDGE_RISING | IRQ_TYPE_EDGE_FALLING:
>>>>>>>> +        value ^= 1 << bit;
>>>>>>>> +        break;
>>>>>>>> +
>>>>>>>> +    default:
>>>>>>>> +        return -EINVAL;
>>>>>>>> +    }
>>>>>>>> +
>>>>>>>> +    tegra_pmc_writel(pmc, value, offset);
>>>>>>> Shouldn't the WAKE_LEVEL be latched as well?
>>>> WAKE_LEVELs dont need any latch as they are the levels SW sets for wake
>>>> trigger and they are not status
>>> Okay.
>>>
>>> [snip]