Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
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
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>
 <71a88a9c-a542-557a-0eaa-3c90112dee0e@nvidia.com>
 <70ad28cb-c268-cbbe-36f5-39df26617d8e@gmail.com>
 <629826f9-c453-386a-9e88-bd64d23b8eab@nvidia.com>
 <71c8cab1-bf72-c073-be30-4263c6b7c871@gmail.com>
 <97096b6c-f2f5-b82a-b172-802f4a06d1af@nvidia.com>
From:   Dmitry Osipenko <digetx@gmail.com>
Message-ID: <a58de350-f6ce-9308-1ae0-885e732b575d@gmail.com>
Date:   Tue, 23 Jul 2019 06:43:08 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101
 Thunderbird/60.7.2
MIME-Version: 1.0
In-Reply-To: <97096b6c-f2f5-b82a-b172-802f4a06d1af@nvidia.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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.

[snip]