Depending on how you look at it, you can either say that:
a) There is a PDC hardware issue (with the specific IP rev that exists
   on sc7180) that causes the PDC not to work properly when configured
   to handle dual edges.
b) The dual edge feature of the PDC hardware was only added in later
   HW revisions and thus isn't in all hardware.

Regardless of how you look at it, let's work around the lack of dual
edge support by only ever letting our parent see requests for single
edge interrupts on affected hardware.

NOTE: it's possible that a driver requesting a dual edge interrupt
might get several edges coalesced into a single IRQ.  For instance if
a line starts low and then goes high and low again, the driver that
requested the IRQ is not guaranteed to be called twice.  However, it
is guaranteed that once the driver's interrupt handler starts running
its first instruction that any new edges coming in will cause the
interrupt to fire again.  This is relatively commonplace for dual-edge
gpio interrupts (many gpio controllers require software to emulate
dual edge with single edge) so client drivers should be setup to
handle it.

Fixes: e35a6ae0 ("pinctrl/msm: Setup GPIO chip in hierarchy")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200714080254.v3.1.Ie0d730120b232a86a4eac1e2909bcbec844d1766@changeidSigned-off-by: Linus Walleij <linus.walleij@linaro.org>