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

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Date:   Mon, 26 Nov 2018 11:32:12 -0800
From:   Tony Lindgren <tony@...mide.com>
To:     Thierry Reding <treding@...dia.com>
Cc:     Peter Ujfalusi <peter.ujfalusi@...com>,
        Jon Hunter <jonathanh@...dia.com>,
        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>
Subject: Re: omap5 fixing palmas IRQ_TYPE_NONE warning leads to gpadc timeouts

* Thierry Reding <treding@...dia.com> [181126 10:25]:
> On Mon, Nov 26, 2018 at 11:49:54AM +0200, Peter Ujfalusi wrote:
> > The register map documentation I have states the following:
> > bit7 INT_POLARITY Select the polarity of the INT output line
> > 0: Interrupt line (INT) is low when interrupt is pending (default) RW
> > 1: Interrupt line (INT) is high when interrupt is pending
> > 
> > By default the Palmas irq is active low.
> 
> That would confirm that the driver code is correct. My understanding is
> that the PMC on Tegra expects a low-active IRQ from the PMIC, so we need
> to invert the interrupt again in the PMC.

But then why Tegra need to set PALMAS_POLARITY_CTRL_INT_POLARITY
if dts has IRQ_TYPE_LEVEL_HIGH? Shouldn't the Palmas default low
setting be correct for Tegra if PMC expects active-low interrupt
and then inverts it for GIC?

What seems to make most sense for me right now is either
this option A:

1. Palmas TRM has the INT_POLARITY register misdocumented
   the wrong way around

2. Tegra really gets a level-low interrupt now from
   Palmas with PALMAS_POLARITY_CTRL_INT_POLARITY set and
   then inverts it to level-high for GIC

3. Omap5 wakeupgen does not invert the interrupt for GIC
   and needs PALMAS_POLARITY_CTRL_INT_POLARITY cleared
   for level-high interrupt from Palmas that gets passed
   as level-high interrupt to GIC

Or else option B:

1. Palmas TRM is correct for INT_POLARITY register

2. Tegra should not set PALMAS_POLARITY_CTRL_INT_POLARITY
   as Tegra PMC already translates Palmas level-low interrupt
   to level-high for GIC

3. Omap5 wkupgen also translates palmas interrupt and must
   not set PALMAS_POLARITY_CTRL_INT_POLARITY

Anybody got better explanations?

BTW, this interrupt is pretty easy to test with the
rtctest tool in Linux kernel:

tools/testing/selftests/rtc/rtctest.c

Regards,

Tony