linux-kernel - Re: omap5 fixing palmas IRQ_TYPE_NONE warning leads to gpadc timeouts

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Message-ID: <725df8e7-4aff-3751-d0b0-809b89e882e5@nvidia.com>
Date:   Tue, 20 Nov 2018 11:14:16 +0000
From:   Jon Hunter <jonathanh@...dia.com>
To:     Tony Lindgren <tony@...mide.com>,
        Peter Ujfalusi <peter.ujfalusi@...com>
CC:     Belisko Marek <marek.belisko@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        <linux-omap@...r.kernel.org>,
        "Dr. H. Nikolaus Schaller" <hns@...delico.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Thierry Reding <treding@...dia.com>
Subject: Re: omap5 fixing palmas IRQ_TYPE_NONE warning leads to gpadc timeouts


On 19/11/2018 17:14, Tony Lindgren wrote:
> Hi,
> 
> * Tony Lindgren <tony@...mide.com> [181119 16:19]:
>> * Peter Ujfalusi <peter.ujfalusi@...com> [181119 10:16]:
>>> On 2018-11-13 20:06, Tony Lindgren wrote:
>>>> Looks like the IRQ_TYPE_NONE issue still is there for omap5 and
>>>> should be fixed with IRQ_TYPE_HIGH.
>>>>
>>>> No idea about why palmas interrupts would stop working though,
>>>> Peter, do you have any ideas on this one?
>>>
>>> No, I don't.
>>> The INT polarity can be changed in Palmas.
>>> based on the pdata->irq_flags (queried via irqd_get_trigger_type())
>>> the code  configures it:
>>>
>>> if (pdata->irq_flags & IRQ_TYPE_LEVEL_HIGH)
>>> 	reg = PALMAS_POLARITY_CTRL_INT_POLARITY;
>>> else
>>> 	reg = 0;
>>>
>>> and we pass the same irq_flags to the regmap_add_irq_chip()
>>> IRQ_TYPE_LEVEL_HIGH == IRQF_TRIGGER_HIGH == 0x00000004
>>>
>>> A change in DT should be enough, no need to patch palmas.c, imho.
>>
>> But it's not. I'm now wondering if wakeupgen is inverting the
>> polarity for this interrupt?
>>
>> GIC docs say this about SPI interrupts:
>>
>> "SPI is triggered on a rising edge or is active-HIGH level-sensitive."
>>
>> So when setting IRQ_TYPE_LEVEL_HIGH in dts, we still must not
>> invert the polarity in palmas while tegra needs to. So either
>> tegra114 hardware is inverting the polarity, or omap5 wakeupgen
>> is.
>>
>> Does the palmas trm say which way PALMAS_POLARITY_CTRL
>> triggers if PALMAS_POLARITY_CTRL_INT_POLARITY is set?
>>
>> Also note that dra7 is using a gpio for palmas interrupt.
> 
> Well so commit 7e9d474954f4 ("ARM: tegra: Correct polarity for
> Tegra114 PMIC interrupt") states that tegra114 inverts the
> polarity of the PMIC interrupt. So adding Jon and Thierry to Cc.

Yes Tegra can invert the polarity of the PMIC interrupt.

> So it seems that commit df545d1cd01a ("mfd: palmas: Provide
> irq flags through DT/platform data") wrongly sets the
> PALMAS_POLARITY_CTRL_INT_POLARITY on IRQ_TYPE_LEVEL_HIGH
> while it should set it on IRQ_TYPE_LEVEL_LOW.
> 
> I think the fix needs to set the polarity using
> of_machine_is_compatible() and probably also add a new
> compatible to palmas.c for "ti,palmas-tegra114" to properly
> deal with the inverted interrupt. Or add a property for
> "interrupt-inverted". In any case, it seems that the
> of_machine_is_compatible() is also needed too to avoid
> breaking use with dtb files.
> 
> Jon & Thierry, can you guys please check and confirm this?
I don't fully understand what is being discussed here, but my
understanding is that the palmas interrupt is active low.

Let me know if this helps.

Cheers
Jon

-- 
nvpublic