Question: SPEAr PLGPIO irq_enable on PREEMPT_RT and regmap updates

[Runyu Xiao]

Hi,

Thanks everyone for the feedback.

I will not send the irq_bus_sync_unlock/shadow-state patch for now. From
Sebastian's comments, it sounds like the more important question is
whether this should be handled at the regmap locking/cache level, or by
using a raw lock only where the regmap path is known to be safe.

Herve, your point about other GPIO controllers is fair. I should not
treat PLGPIO as special without checking the wider pattern. I will look
at other irq_enable/irq_disable users that combine irqchip callbacks,
driver spinlocks and regmap_update_bits(), and compare whether they are
using MMIO/flat cache/raw regmap locking or a sleepable regmap path.

For the current PLGPIO draft, I will hold it back until I can answer
whether the right fix belongs in this driver or in the common regmap/GPIO
pattern.

Thanks,
Runyu