Re: [PATCH] gpiolib: acpi: Do not set the IRQ type if the IRQ is already in use

[Hans de Goede <hdegoede@xxxxxxxxxx>]

Hi,

On 11/23/21 10:36, Andy Shevchenko wrote:
> On Mon, Nov 22, 2021 at 11:04:16PM +0100, Hans de Goede wrote:
>> If the IRQ is already in use, then acpi_dev_gpio_irq_get_by() really
>> should not change the type underneath the current owner.
>>
>> I specifically hit an issue with this an a Chuwi Hi8 Super (CWI509) Bay
>> Trail tablet, when the Boot OS selection in the BIOS is set to Android.
>> In this case _STA for a MAX17047 ACPI I2C device wrongly returns 0xf and
>> the _CRS resources for this device include a GpioInt pointing to a GPIO
>> already in use by an _AEI handler, with a different type then specified
>> in the _CRS for the MAX17047 device. Leading to the acpi_dev_gpio_irq_get()
>> call done by the i2c-core-acpi.c code changing the type breaking the
>> _AEI handler.
>>
>> Now this clearly is a bug in the DSDT of this tablet (in Android mode),
>> but in general calling irq_set_irq_type() on an IRQ which already is
>> in use seems like a bad idea.
> 
> I'm fine with the change, one comment below, though.
> 
>> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
>> ---
>>  drivers/gpio/gpiolib-acpi.c | 8 ++++++--
>>  1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
>> index 985e8589c58b..24cd86bf2c4c 100644
>> --- a/drivers/gpio/gpiolib-acpi.c
>> +++ b/drivers/gpio/gpiolib-acpi.c
>> @@ -1056,8 +1056,12 @@ int acpi_dev_gpio_irq_get_by(struct acpi_device *adev, const char *name, int ind
>>  			irq_flags = acpi_dev_get_irq_type(info.triggering,
>>  							  info.polarity);
>>  
>> -			/* Set type if specified and different than the current one */
>> -			if (irq_flags != IRQ_TYPE_NONE &&
>> +			/*
>> +			 * If the IRQ is not already in use then set type
>> +			 * if specified and different than the current one.
>> +			 */
>> +			if (can_request_irq(irq, irq_flags) &&
>> +			    irq_flags != IRQ_TYPE_NONE &&
>>  			    irq_flags != irq_get_trigger_type(irq))
>>  				irq_set_irq_type(irq, irq_flags);
> 
> What about issuing a debug (?) message
> 
> 			if (can_request_irq(irq, irq_flags) {
> 				if (irq_flags != IRQ_TYPE_NONE &&
> 				    irq_flags != irq_get_trigger_type(irq))
> 					irq_set_irq_type(irq, irq_flags);
> 			} else {
> 				dev_dbg(..., FW_BUG "IRQ %d already in use\n", irq);
> 			}
> 
> ?

That is a good idea, I would even be fine with making it a dev_warn, because it
really is a FW_BUG if we get here. If we turn out to hit this too much we
can always lower the log level later.

Shall I submit a v2 with your suggestion, but then using a dev_warn ?

Regards,

Hans