On Monday, August 27, 2012, Aaron Lu wrote:
> Currently, when we are trying to get the power state of an acpi device,
> we will do the following:
> If device is not power manageable, init its power state as its parent or
> if it does not have a parent, init as D0;
> If device is power manageable, evaluate _PSC and then refine with
> acpi_power_get_inferred_state.
>
> But there exist some devices with _PSx defined, but no _PSC or _PRx.
> It is power manageable, but the above method to get power state does
> not cover this case and its power state will be UNKNOWN(255).
>
> So change the check of power manageable to whether _PSC and _PRx
> defined.
>
> Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx>
Applied to the linux-next branch of the linux-pm.git tree.
I think it should go to -stable too and therefore it would be good to have
it in v3.6, so I'd like to push it to Linus for -rc5, if Len has no objections.
Thanks,
Rafael
> ---
> drivers/acpi/bus.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> index 9628652..b564e6d 100644
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -207,7 +207,8 @@ static int __acpi_bus_get_power(struct acpi_device *device, int *state)
> if (!device || !state)
> return -EINVAL;
>
> - if (!device->flags.power_manageable) {
> + if (!device->power.flags.explicit_get &&
> + !device->power.flags.power_resources) {
> /* TBD: Non-recursive algorithm for walking up hierarchy. */
> *state = device->parent ?
> device->parent->power.state : ACPI_STATE_D0;
>
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