On Fri, Aug 5, 2016 at 1:38 AM, Linus Walleij [off-list ref] wrote:

The Qualcomm PMIC GPIO and MPP lines are problematic: the
are fetched from the main MFD driver with platform_get_irq()
which means that at this point they will all be assigned the
flags set up for the interrupts in the device tree.

That is problematic since these are flagged as rising edge
and an this point the interrupt descriptor is assigned a
rising edge, while the only thing the GPIO/MPP drivers really
do is issue irq_get_irqchip_state() on the line to read it
out and to provide a .to_irq() helper for *other* IRQ
consumers.

If another device tree node tries to flag the same IRQ
for use as something else than rising edge, the kernel
irqdomain core will protest like this:

  type mismatch, failed to map hwirq-NN for <FOO>!

Which is what happens when the device tree defines two
contradictory flags for the same interrupt line.

To work around this and alleviate the problem, assign 0
as flag for the interrupts taken by the PM GPIO and MPP
drivers. This will lead to the flag being unset, and a
second consumer requesting rising, falling, both or level
interrupts will be respected. This is what the qcom-pm*.dtsi
files already do.

Switched to using the symbolic name IRQ_TYPE_NONE so that
we get this more readable.

Cc: stable at vger.kernel.org
Fixes: bce360469676 ("ARM: dts: apq8064: add pm8921 mpp support")
Fixes: 874443fe9e33 ("ARM: dts: apq8064: Add pm8921 mfd and its gpio node")
Cc: Srinivas Kandagatla <redacted>
Cc: Stephen Boyd <redacted>
Cc: Bj?rn Andersson <redacted>
Cc: Ivan T. Ivanov <redacted>
Cc: John Stultz <redacted>
Cc: Andy Gross <redacted>
Signed-off-by: Linus Walleij <redacted>
---
I vaguely remember John having problems with interrupts
on the Nexus 7 that could be related to this so involving
him on these patches.

Yea. Thanks for including me. Unfortunately these patches don't
resolve the problem I'm seeing (I still don't get any interrupts from
the volume/power buttons), and I still have to revert "irqdomain:
Don't set type when mapping an IRQ" to get things working.

thanks
-john