linux-kernel - BUG? genirq: irq 14 uses trigger mode 8; requested 0

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Date:   Tue, 1 Nov 2016 15:02:31 +0200
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Jon Hunter <jonathanh@...dia.com>
Cc:     Marc Zyngier <marc.zyngier@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: BUG? genirq: irq 14 uses trigger mode 8; requested 0

Hi,

I started seeing following messages on Intel Broxton when the
pinctrl/GPIO driver [1] loads:

  [    0.645786] genirq: irq 14 uses trigger mode 8; requested 0

The driver shares interrupt with other GPIO "communities" or banks so it
uses request_irq() instead of irq_set_chained_handler_and_data(). The
driver does not specify IRQ flags as those come from ACPI resources.

This started happen after commit 4b357daed698 ("genirq: Look-up trigger
type if not specified by caller").

I think this is what happens:

  1. ACPI platform sets up the interrupt according what is in the _CRS
  of the GPIO device. This ends up setting trigger type for irq_data of
  the irq.

  2. First GPIO device is found and the driver calls request_irq() which
  calls __setup_irq() where shared == 0. 

  3. Since new->flags is read back from irq_data we call __irq_set_trigger()
  passing the flags.

  4. The parent IRQ chip, IO-APIC, does not have ->irq_set_type callback
  so __irq_set_trigger() never calls irq_settings_set_trigger_mask() for
  the desciptor.

  5. The second GPIO device is found and this time shared == 1 so we
  end up comparing nmsk with omsk where nmsk was read from irq_data
  and omsk is read using irq_settings_get_trigger_mask().

  6. Because we never called irq_settings_set_trigger_mask() for the
  descriptor, omsk is 0 and we print out a warning:

  [    0.645786] genirq: irq 14 uses trigger mode 8; requested 0

If I revert commit 4b357daed698 the warning goes away.

Do you have any ideas how to get rid of the warning properly?

Thanks in advance.

[1] drivers/pinctrl/intel/pinctrl-intel.c