On Monday, September 10, 2012, Aaron Lu wrote:
> On Fri, Sep 07, 2012 at 08:32:55PM +0200, Rafael J. Wysocki wrote:
> > On Friday, September 07, 2012, Aaron Lu wrote:
> > > On 09/07/2012 07:46 PM, Rafael J. Wysocki wrote:
> > > >> Yes, on a test system, when I try to put a device into D3 cold and ACPI
> > > >> will complain that I can't due to its parent is in a even lower power
> > > >> state UNKNOWN(255), this parent device is power manageable but has no
> > > >> _PSC and _PRx defined.
> > > >
> > > > Perhaps we can force _PS0 for such devices to start with, so that we know
> > > > for sure that the initial state is D0?
> > >
> > > Sounds good, I'll update the patch, thanks for the advice.
> >
> > Actually, I suppose we can do something like the appended patch instead.
> >
> > I wonder if it works around the particular problem you're seeing?
>
> Yes, thanks.
>
> Reviewed-by: Aaron Lu <aaron.lu@xxxxxxxxx>
Cool, thanks for testing!
I'll resend it shortly with a proper changelog.
Thanks,
Rafael
> > ---
> > drivers/acpi/bus.c | 11 ++++++++++-
> > 1 file changed, 10 insertions(+), 1 deletion(-)
> >
> > Index: linux/drivers/acpi/bus.c
> > ===================================================================
> > --- linux.orig/drivers/acpi/bus.c
> > +++ linux/drivers/acpi/bus.c
> > @@ -229,7 +229,16 @@ static int __acpi_bus_get_power(struct a
> > result = psc;
> > }
> > /* The test below covers ACPI_STATE_UNKNOWN too. */
> > - if (result <= ACPI_STATE_D2) {
> > + if (result == ACPI_STATE_D0) {
> > + /*
> > + * If we were unsure about the device parent's power state up to
> > + * this point, the fact that the device is in D0 implies that
> > + * the parent has to be in D0 too.
> > + */
> > + if (device->parent
> > + && device->parent->power.state == ACPI_STATE_UNKNOWN)
> > + device->parent->power.state = ACPI_STATE_D0;
> > + } else if (result <= ACPI_STATE_D2) {
> > ; /* Do nothing. */
> > } else if (device->power.flags.power_resources) {
> > int error = acpi_power_get_inferred_state(device, &result);
>
>
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