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: <5ccf48f4-45dc-3a30-3d6a-cce066f01270@redhat.com>
Date:   Mon, 18 Jan 2021 14:13:50 +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 2:02 PM, Mark Brown wrote:
> On Sun, Jan 17, 2021 at 10:22:50PM +0100, Hans de Goede wrote:
> 
>> +	/*
>> +	 * Some DSDTs wrongly declare the IRQ trigger-type as IRQF_TRIGGER_FALLING
>> +	 * The IRQ line will stay low when a new IRQ event happens between reading
>> +	 * the IRQ status flags and acknowledging them. When the IRQ line stays
>> +	 * low like this the IRQ will never trigger again when its type is set
>> +	 * to IRQF_TRIGGER_FALLING. Correct the IRQ trigger-type to fix this.
>> +	 */
>> +	arizona->pdata.irq_flags = IRQF_TRIGGER_LOW;
> 
> Are you sure that all the relevant interrupt controllers support active
> low interrupts?  There were issues on some systems with missing support
> for active low interrupts (see the bodge in wm8994-irq.c to work around
> them) - it's entirely likely that there are DSDTs that are just plain
> buggy here but if someone's copying and pasting it smells like there may
> be some systems that actually need an edge triggered interrupt that
> they're getting it from.

I'm only aware of one series of devices / models which actually
use the combination of ACPI enumeration and the WM5102 codec, and that
is the Lenovo Yoga Tablet 2 series (in 8, 10 and 13 inch versions
shipping with both Windows and Android). These all use a Bay Trail
SoC which is capable of using active low interrupts.

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.

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.

Regards,

Hans



> 
>> +
>> +	/* Wait 200 ms after jack insertion */
>> +	arizona->pdata.micd_detect_debounce = 200;
>> +
>> +	/* Use standard AOSP values for headset-button mappings */
>> +	arizona->pdata.micd_ranges = arizona_micd_aosp_ranges;
>> +	arizona->pdata.num_micd_ranges = ARRAY_SIZE(arizona_micd_aosp_ranges);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct acpi_device_id arizona_acpi_match[] = {
>> +	{
>> +		.id = "WM510204",
>> +		.driver_data = WM5102,
>> +	},
>> +	{
>> +		.id = "WM510205",
>> +		.driver_data = WM5102,
>> +	},
>> +	{ }
>> +};
>> +MODULE_DEVICE_TABLE(acpi, arizona_acpi_match);
>> +#else
>> +static int arizona_spi_acpi_probe(struct arizona *arizona)
>> +{
>> +	return -ENODEV;
>> +}
>> +#endif
>> +
>>  static int arizona_spi_probe(struct spi_device *spi)
>>  {
>>  	const struct spi_device_id *id = spi_get_device_id(spi);
>> @@ -77,6 +191,12 @@ static int arizona_spi_probe(struct spi_device *spi)
>>  	arizona->dev = &spi->dev;
>>  	arizona->irq = spi->irq;
>>  
>> +	if (has_acpi_companion(&spi->dev)) {
>> +		ret = arizona_spi_acpi_probe(arizona);
>> +		if (ret)
>> +			return ret;
>> +	}
>> +
>>  	return arizona_dev_init(arizona);
>>  }
>>  
>> @@ -104,6 +224,7 @@ static struct spi_driver arizona_spi_driver = {
>>  		.name	= "arizona",
>>  		.pm	= &arizona_pm_ops,
>>  		.of_match_table	= of_match_ptr(arizona_of_match),
>> +		.acpi_match_table = ACPI_PTR(arizona_acpi_match),
>>  	},
>>  	.probe		= arizona_spi_probe,
>>  	.remove		= arizona_spi_remove,
>> -- 
>> 2.28.0
>>