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 12:01, Andy Shevchenko wrote:
> On Tue, Nov 23, 2021 at 12:59 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>> 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 ?
> 
> Please do, it will be slightly easier for me.

Ok, I've just send out a v2. Note I forgot to add -v2 to format-patch so
the subject does not say it is v2, sorry.

Regards,

Hans