Re: [PATCH] acpi: bus: handle power manageable but no _PSC/_PRx case

["Rafael J. Wysocki" <rjw@sisk.pl>]

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@intel.com>

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);
> 
>