drivers/gpio PCA9555 - epoll_wait(2) misses first irq after setting an irq mask...

[metelik]

When ones changes the state of any input pins of a PCA9555 chip before setting up the IRQ mask through i.e. SysFS e.g.

echo "both" > /sys/class/gpio/gpioXYZ/edge the epoll_wait shall not exit on the subsequent change of the GPIO state.
The reason behind it is that the IRQ status is not being saved when the IRQ is masked.

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