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

[Andy Shevchenko <andy.shevchenko@xxxxxxxxx>]

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.

-- 
With Best Regards,
Andy Shevchenko