linux-kernel - Re: [PATCH v3 3/5] mfd: arizona: Add support for ACPI enumeration of WM5102 connected over SPI

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Message-ID: <a1ea81b6-8aff-274c-f1b2-a06a27650b25@redhat.com>
Date:   Wed, 20 Jan 2021 20:18:25 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Lee Jones <lee.jones@...aro.org>,
        Cezary Rojewski <cezary.rojewski@...el.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Liam Girdwood <liam.r.girdwood@...ux.intel.com>,
        Jie Yang <yang.jie@...ux.intel.com>,
        patches@...nsource.cirrus.com, linux-kernel@...r.kernel.org,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        alsa-devel@...a-project.org,
        Christian Hartmann <cornogle@...glemail.com>
Subject: Re: [PATCH v3 3/5] mfd: arizona: Add support for ACPI enumeration of
 WM5102 connected over SPI

Hi,

On 1/18/21 2:34 PM, Mark Brown wrote:
> On Mon, Jan 18, 2021 at 02:13:50PM +0100, Hans de Goede wrote:
> 
>> More in general I'm not aware of any (recent-ish) x86 GPIO controllers
>> not being able to do active low interrupts. In theory we could hit this
>> code path on ARM devices using ACPI enumeration, but I don't think it
>> is likely we will see a combination of ARM + ACPI enumeration +
>> WM5102 + GPIO controller not capable of active-low interrupts.
> 
> I've not seen this issue on any ARM based systems.
> 
>> This overriding of the flags definitely is necessary on the Lenovo
>> devices in question. I could add a
>> "if (dmi_name_in_vendors("LENOVO"))" guard around it, but that
>> seems unnecessary.
> 
> Possibly just an update to the comment to make it clear that some
> firmwares might legitimately set the flag?

Ok, I've extended the comment above the override of the irq-flags with
the following paragraph for v4 of this patch-set:

         * Note theoretically it is possible that some boards are not capable
         * of handling active low level interrupts. In that case setting the
         * flag to IRQF_TRIGGER_FALLING would not be a bug (and we would need
         * to work around this) but sofar all known usages of IRQF_TRIGGER_FALLING
         * are a bug in the boards DSDT.

Regards,

Hans