On Mon, Jan 7, 2019 at 4:42 PM Thomas Petazzoni
[off-list ref] wrote:

This patch almost solves the problem. It doesn't work as-is, because it
assumes that runtime PM is used by all GPIO controllers, which is not
the case. When runtime PM is not enabled, pm_runtime_get_sync() fails
with -EACCES, and the whole gpiochip_irq_reqres() function aborts.

(...)

However, I must say that from a design perspective, I am not a big fan
of this solution. Indeed for the normal GPIO ->request() and ->free()
hooks, it is currently the GPIO driver itself that is responsible for
runtime PM get/put, so it would be weird to have the runtime PM get/put
for the IRQ request/free be done by the GPIO core.

I believe that either the GPIO core should be in charge of the entire
runtime PM interaction, or it should entirely be the responsibility of
each GPIO controller driver. Having a mixed solution seems very
confusing.

My stance is that the driver is responsible of enabling and managing
runtime PM for its hardware block(s).

Runtime PM in the core should only be added if the core needs to
be aware about it, such as is the case when e.g. a block device
needs to drain its write buffer before going to runtime sleep.

I fail so see why the GPIO core need to be aware about this.

Yours,
Linus Walleij

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel