[RFC PATCH v2 1/3] PCI: rockchip: Add support for pcie wake irq

* Brian Norris [off-list ref] [171222 23:23]:

+ Rafael to this thread

On Wed, Dec 20, 2017 at 11:19:12AM -0800, Tony Lindgren wrote:

quoted

* Brian Norris [off-list ref] [171219 00:50]:

quoted

On Wed, Aug 23, 2017 at 09:32:39AM +0800, Jeffy Chen wrote:

Did this problem ever get resolved? To be clear, I believe the problem
at hand is:

(a) in suspend/resume (not runtime PM; we may not even have runtime PM
support for most PCI devices)

It seems it should be enough to implement runtime PM in the PCI
controller. Isn't each PCI WAKE# line is wired from each PCI device
to the PCI controller?

No, not really. As discussed in later versions of this thread already,
the WAKE# hierarchy is orthogonal to the PCI hierarchy, and I think we
settled that it's reasonable to just consider this as a 1-per-device
thing, with each device "directly" attached to the PM controller. While
sharing could happen, that's something we decided to punt on...didn't
we?

Sounds like we need a confirmation from some hardware people on
this if the PCI device WAKE# can be wired to PCI controller or
to a separate PM controller directly :)

quoted

Then the PCI controller can figure out from which PCI device the
WAKE# came from.

I'm not completely sure of the details, but I believe this *can* be
determined by PME. But I'm not sure it's guaranteed to be supported,
especially in cases where we already have 1:1 WAKE#. So we should be
*trying* to report this wakeirq info from the device, if possible.

If a PCI device has it's WAKE# wired directly to a PM controller
instead of the PCI controller, then it seems that the PCI controller
should be woken up and then presumably the regular PCI device
interrupts will take care of the rest.

Or else I'd say if the driver for the PCI device in some custom
case needs to do something specific, then having that driver
implement PM runtime makes sense. Naturally we want to avoid a
dependency where all the possible drivers would need to implement
PM runtime, I doubt that's needed though.

Regards,

Tony