Re: [RESEND] [PATCH 2/4] ACPI: Get the device power state in the course of scanning device

Zhao Yakui
2008-08-11T07:37:24Z

On Mon, 2008-08-11 at 08:52 +0200, Andi Kleen wrote:
> On Mon, Aug 11, 2008 at 03:02:20PM +0800, Zhao Yakui wrote:
> > On Mon, 2008-08-11 at 08:45 +0200, Andi Kleen wrote:
> > > On Mon, Aug 11, 2008 at 02:55:05PM +0800, Zhao Yakui wrote:
> > > > Subject:ACPI: Get the device power state in the course of scanning device
> > > > From: Zhao Yakui <yakui.zhao@intel.com>
> > > >
> > > > Get the device power state in the course of scanning device if the device
> > > > power flag is power_managable. i.e. The device has the _PSx/_PRx object.
> > > >
> > > > At the same time before the drivers/acpi/power module is loaded, there is no
> > > > relation between acpi_power_resource and acpi device. So the first parameter
> > > > of acpi_power_get_state is changed to acpi_handle.
> > > >
> > > > http://bugzilla.kernel.org/show_bug.cgi?id=8049
> > > > http://bugzilla.kernel.org/show_bug.cgi?id=11000
> > >
> > > Seems to be an pretty old bug. I assume it's not critical
> > > enough to require pushing into .27?
> > Yes. It is not critical.
> > But in fact windows can work well on such broken BIOS. In order to make
>
> Any guess how do they do that? Do they have a blacklist for this case?
I do such a test by using the KVM and find that there is no power state
check during power transition. So it will be reasonable that Linux also
disables power state check during power transition.

> > Linux be compatible with this broken BIOS, it will be OK to merge them.
>
> The option is fine since it is off by default, but I'm a little scaried
> about the init sequence ordering for .27. That might break something.
After the patch is applied, Linux will still do the power state check
unless the boot option of "acpi.power_nocheck=1" is added. In such case
it won't affect anything.
In fact we expect that the boot option of "acpi.power_nocheck=1" becomes
the default. But we will have to wait for more response. Only after more
tests are done, it will be OK.

what the init sequence ordering for .27 means?

thanks.

> -Andi
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