Re: [RESEND patch 2.6.25] ACPI uses device_may_wakeup() policy inputs

[David Brownell <david-b@pacbell.net>]

[ grr, mousepad sent an incomplete message for me ... ]

On Monday 28 April 2008, Zhao Yakui wrote:
> 
> > > But after the patch is applied, some PCI device(the ACPI device with the
> > > _PRW object) can wake the sleeping system by default. And it is totally
> > > opposite to the current flowchart. 
> > 
> > That's not true.  Behavior could only change for devices with
> > drivers which already call pci_enable_wake()!
> 
> Yes. But in fact a lot of PCI device will call pci_enable_wake when the
> system enters the suspend state. And the behaviour will be changed.

I'm not sure what your point is.  That "behavior change" is a bugfix.
The previous behavior was specific to ACPI, and obviously was not what
the driver writer expected.

And it's *NOT* how things work on non-ACPI systems which have both PCI
and functional system suspend/resume.  (Various PowerPC, MIPS, and ARM
systems meet those requirements, as I understand.)

I sympathize with the desire to avoid driver-related surprises.  In
this case, it's trivial to disable that behavior using sysfs.  And I
believe you'll observe that not many drivers could actually turn up
surprises here:  who calls pci_enable_wake()?

- Dave
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