gpio-dwapb: reason for storing & restoring registers on suspend/resume

[Magnus Olsson <magnus@xxxxxxxxxx>]

Hi,

During PM suspend(), the gpio-dwapb.c driver store registers for each 
port into a context. For Port A it also stores IRQ settings, since it 
can act as a wake-up source. During resume(), the registers are restored 
from the context.

What is the purpose of these store & restore? Because the GPIO 
controller also is a wake-up source, it will never sleep and AFAIK the 
registers remain untouched throughout a suspend/resume cycle.

When port A is used to wake up the system (e.g enable_irq_wake() has 
enabled wake_en bits in the driver), I sometimes see calls to gpio-dwapb 
irq_mask() before the driver is resumed(). When resume() later on 
occurs, any changes made to the registers (in my case IRQ mask) while 
the driver is suspended are therefore lost.

This race between resume() and irq_mask() (called by threaded wake-up 
IRQ handler) sometime causes IRQ to remain masked indefinitely, 
depending on when the wake-up IRQ arrives.

Is this intentional? Can anyone shed light on why the store & restore 
mechanism exists in the first place?

BR,
 Magnus Olsson.