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Subject: Re: [PATCH V6 16/21] soc/tegra: pmc: Add pmc wake support for
 tegra210
From:   Dmitry Osipenko <digetx@gmail.com>
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
References: <1563738060-30213-1-git-send-email-skomatineni@nvidia.com>
 <1563738060-30213-17-git-send-email-skomatineni@nvidia.com>
 <0b3d08ea-4633-8a54-ba66-c3f3146a1ece@gmail.com>
 <ca32c2d8-d752-3ecd-3a3f-232366730c7b@gmail.com>
 <b575ca93-9f34-b07a-1234-ef1ea2a6ddee@gmail.com>
 <66535c01-7079-0192-c992-c25a4d7cdbb9@gmail.com>
Message-ID: <b3326073-23f0-9a8d-535e-e6475b17a56e@gmail.com>
Date:   Tue, 23 Jul 2019 05:10:43 +0300
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23.07.2019 4:52, Dmitry Osipenko пишет:
> 23.07.2019 4:41, Dmitry Osipenko пишет:
>> 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.
> 
> Okay, I re-read the TRM and apparently "latching" just means storing of
> WAKE-event bit in the WAKE-status register if latching is enabled. Hence
> the PMC_CNTRL_LATCHWAKE_EN should be enabled in tegra_pmc_suspend() and
> unset in tegra_pmc_resume().
> 
> Also, apparently, on resume from suspend the interrupt should be
> re-triggered in accordance to the WAKE-status, then the WAKE-status need
> to be cleared.

I'm now also recalling that downstream kernel had some problems in
regards to missing power-button presses on resume from suspend because
input driver reads the GPIO-key state in order to determine the press
status and the GPIO state in already unset at the time when input driver
resumes. Hence it happened sometime that after pressing power button,
device waked up from LP0 and then immediately went into suspend (due to
android's wakelocks).

>>>>> +	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?
>>>>
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>>  static int tegra186_pmc_irq_set_type(struct irq_data *data, unsigned int type)
>>>>>  {
>>>>>  	struct tegra_pmc *pmc = irq_data_get_irq_chip_data(data);
>>>>> @@ -2540,6 +2643,10 @@ static const struct pinctrl_pin_desc tegra210_pin_descs[] = {
>>>>>  	TEGRA210_IO_PAD_TABLE(TEGRA_IO_PIN_DESC)
>>>>>  };
>>>>>  
>>>>> +static const struct tegra_wake_event tegra210_wake_events[] = {
>>>>> +	TEGRA_WAKE_IRQ("rtc", 16, 2),
>>>>> +};
>>>>> +
>>>>>  static const struct tegra_pmc_soc tegra210_pmc_soc = {
>>>>>  	.num_powergates = ARRAY_SIZE(tegra210_powergates),
>>>>>  	.powergates = tegra210_powergates,
>>>>> @@ -2557,10 +2664,14 @@ static const struct tegra_pmc_soc tegra210_pmc_soc = {
>>>>>  	.regs = &tegra20_pmc_regs,
>>>>>  	.init = tegra20_pmc_init,
>>>>>  	.setup_irq_polarity = tegra20_pmc_setup_irq_polarity,
>>>>> +	.irq_set_wake = tegra210_pmc_irq_set_wake,
>>>>> +	.irq_set_type = tegra210_pmc_irq_set_type,
>>>>>  	.reset_sources = tegra210_reset_sources,
>>>>>  	.num_reset_sources = ARRAY_SIZE(tegra210_reset_sources),
>>>>>  	.reset_levels = NULL,
>>>>>  	.num_reset_levels = 0,
>>>>> +	.num_wake_events = ARRAY_SIZE(tegra210_wake_events),
>>>>> +	.wake_events = tegra210_wake_events,
>>>>>  };
>>>>>  
>>>>>  #define TEGRA186_IO_PAD_TABLE(_pad)					     \
>>>>>
>>>>
>>>
>>
>