On Wed, 2009-11-11 at 04:09 +0800, Matthew Garrett wrote: > https://bugzilla.redhat.com/show_bug.cgi?id=531916 describes a system > with a _PSC method for the fan that always returns "on". There's no > benefit in us always requesting the state of the fan when performing > transitions - we want to do everything we can to ensure that the fan turns > on when it should do, not risk hardware damage by believing the hardware > when it tells us the fan is already on. Given that the Leading Other OS(tm) > works fine on this machine, it seems likely that it behaves in much this > way. > sounds reasonable. But how can we get the power state if power resources is not available? In acpi_bus_get_power, why not make acpi_power_get_inferred_state as the first choice, instead of evaluating _PSC? like the patch attached. --- drivers/acpi/bus.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) Index: linux-2.6/drivers/acpi/bus.c =================================================================== --- linux-2.6.orig/drivers/acpi/bus.c +++ linux-2.6/drivers/acpi/bus.c @@ -190,16 +190,17 @@ int acpi_bus_get_power(acpi_handle handl * Get the device's power state either directly (via _PSC) or * indirectly (via power resources). */ - if (device->power.flags.explicit_get) { + + if (device->power.flags.power_resources) { + result = acpi_power_get_inferred_state(device); + if (result) + return result; + } else if (device->power.flags.explicit_get) { status = acpi_evaluate_integer(device->handle, "_PSC", NULL, &psc); if (ACPI_FAILURE(status)) return -ENODEV; device->power.state = (int)psc; - } else if (device->power.flags.power_resources) { - result = acpi_power_get_inferred_state(device); - if (result) - return result; } *state = device->power.state; > Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx> > --- > drivers/acpi/fan.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/drivers/acpi/fan.c b/drivers/acpi/fan.c > index f419849..835b55e 100644 > --- a/drivers/acpi/fan.c > +++ b/drivers/acpi/fan.c > @@ -256,6 +256,7 @@ static int acpi_fan_add(struct acpi_device *device) > goto end; > } > > + device->power.flags.explicit_get = 0; > device->flags.force_power_state = 1; > acpi_bus_set_power(device->handle, state); > device->flags.force_power_state = 0; at least we should clear the explicit_get flag 6 lines above, i.e. before getting the fan state? thanks, rui -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
