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SubjectRe: [PATCH] ACPI / PM: Infer parent power state from child if unknown
On Mon, Sep 10, 2012 at 09:50:22PM +0200, Rafael J. Wysocki wrote:
> 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
> @@ -228,7 +228,16 @@ 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) {

Oops, I just realized that the check here is too early if device does
not have _PSC but _PRx, its parent will miss the chance to get power
state updated :-)

Sorry for not spotting this earlier.

-Aaron

> + /*
> + * 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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