On Fri, Dec 8, 2017 at 5:37 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote: > * Brian Norris <briannorris@xxxxxxxxxxxx> [171207 00:32]: >> On Wed, Dec 06, 2017 at 04:17:54PM -0800, Tony Lindgren wrote: >> > * Brian Norris <briannorris@xxxxxxxxxxxx> [171206 19:36]: >> > > By the way, it seems pretty ambiguous how we want to handle things like >> > > (a) multiple devices sharing the same WAKE# >> > > (b) systems where a slot is swappable >> > > >> > > For (a), the main problem is that if we have to repeat the interrupt >> > > definition in multiple devices, then we have to deal with something like >> > > IRQF_SHARED. That can be done, but it makes it much harder to use the >> > > dedicated wakeirq helpers. >> > >> > This will get messy, let's not go there :) That is unless the hardware >> > really has a single interrupt wired to multiple devices. And in that >> > case almost certainly a custom interrupt handler is needed. >> >> As Rafael mentioned, the spec doesn't clearly delineate a required >> hierarchy to the WAKE# pin, and it's certainly possible to share it. I'm >> fine dodging that question for now, and only writing said custom >> interrupt handler if/when needed. > > OK if the WAKE# pin is shared then PCI (or hardware specific?) code needs > to figure out from where it came from. Right. Basically, that would need a list (or equivalent) of devices sharing the wakeup IRQ and if that triggers, it needs to walk the list and call pci_pme_wakeup() for all devices in it. >> But device tree bindings are "forever", so it seems reasonable to at >> least agree how it should be defined. > > Well that's why we're just using the existing interrupts-extended > binding there :) It does not leave out the option for shared interrupts, > it's just that drivers/base/power/wakeirq.c can't deal with them in a > sane way or at least we'd have to add a flag to not enable/disable the > wakeirq automatically. I think that the binding needs to be sort-of PCI-specific to cover the shared case. I'm not sure if there are any other buses needing that (they would need to define standard PM registers as PCI does). -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
