On Monday 08 September 2008, Li, Shaohua wrote:
>
> >> + * @wakeup_event: Checks if a wakeup event occurs.
> >> + * If yes, wakeup event should be disabled.
> >
> >And ... what else?? What does the return value indicate?
> >Should anything be done with it other than printing it out
> >if it's nonzero and we're debugging?
>
> Return 0 if the device invokes a wakeup event. In this case, driver
> should clear/disable wakeup event.
> Return < 0 if device didn't invoke wakeup.
So it's effectively "bool"? I'd declare it as "bool" then...
and rename it to sound like a predicate; "is_wakedev()" maybe.
> If device follows standard wakeup mechanism which bus level can
> handle, driver isn't required to provide this callback.
There seems to be a semi-hidden distinction between bus-level
code and device-level code. Somewhat apparent in later code;
but not at all clear in this initial set-the-stage patch.
> >> @@ -151,6 +153,7 @@ struct pm_ops {
> >> int (*thaw)(struct device *dev);
> >> int (*poweroff)(struct device *dev);
> >> int (*restore)(struct device *dev);
> >> + int (*wakeup_event)(struct device *dev);
> >
> >My reaction to adding this method is: why do it here rather
> >than at the bus level?
Your answer probably should have been: "The recent method
reshuffling makes that method work both at the level of the
'struct bus_type' and at the level of 'struct device'. So
this _does_ add it at the bus level."
:)
> >In my particular experience there are two basic types of wakeup
> >event:
> >
> > ...
> >
> > * ACPI GPEs. Bus-specific ... and similar to GPIO IRQs.
> > Also sharable; bytecode is used to map the GPE and
> > some register state to the ACPI device(s) which
> > issued that GPE.
>
> This isn't bus specific.
It's bus-specific in the sense of "ACPI bus" (/sys/bus/acpi).
If the DSDT defines a GPE and maps it to an ACPI device, it will
follow those rules.
Devices not on the "ACPI bus" -- like add-on PCI cards, USB
peripherals, and other devices which have some such ACPI device
higher in the driver model tre -- don't use GPEs to wake up.
(An ancestral device may well do so: a PCI bridge, a USB
host controller, etc.)
> ACPI devices can map to any physical devices, like PCI, IDE
> drive, PNP device. In this case, a bus specific mechanism can't
> handle all.
Sure it can. And it'd be more natural to do it that way too.
I'd be tempted to call them from ACPI like
struct device *dev;
acpi_handle adev;
/* adev received a wake event notification */
...
dev = acpi_get_physical_device(adev);
if (dev) {
/* this chunk of code should probably live in
* drivers/base/power/... somewhere and be
* part of this patch 1/5 so it's more clear
* what the infrastructure is doing.
*/
if (... && dev->bus->pm.base->is_wakedev(dev)) {
... call dev->driver->pm.resume(dev)
... else if resume is null, issue diagnostic
} else {
... report suitable generic confusion ...
}
} else {
... report ACPI-specific confusion ...
}
...
When that's a PCI device -- bridge or otherwise -- that
would call something resembling your patch #3 (but fixed
to handle the case of PCI bridges, so add-in cards will
work properly).
And for a non-ACPI system, whatever IRQ handler receives the
PME# signal would just call that chunk of code for the PCI
root bridge(s) it handles. All done. :)
> For example the UHCI case. A GPE is fired, we need to clear/disable
> the wakeup event. PCI bus can't handle it, as UHCI has special
> registers for this, so we need call into device specific handling.
So the bus-level PCI operation would end up with a device
that's either (a) known to have fired PME#, or (b) known
to be a device with legacy PM -- like UHCI -- which it's
presuming has been wakeup-enabled.
Then in the (a) case it can clear PME# the normal way, and
would rarely need to do anything else.
While in the (b) case the UHCI driver would need to have
provided some device-specific -- not bus-generic -- op
called like dev->driver->pm.is_wakeup(), to diddle those
registers (only for Intel silicon, not UHCI from VIA or
Genesys or anyone else).
I think I'm getting a bit more clear on what you're trying
to do with this. Restructure it a bit and I will be able
to see that from reading the code (as will others). :)
- Dave
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