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>
-Aaron
>
> 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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