>Why do we bother with the "acpi_bus_get_power" at all? The problem >Matthew is seeing wouldn't happen at all if we just deleted everything >in the force_power_state block. > >Then we could execute _ON, _PS0, etc for a device that is already on. >Does that cause bad things to happen? I assume the fan probably works >as desired under Windows, so they probably do something like this. This would work for _PSx (if device power states are controlled via _PSx methods, we should only execute method, defined for desired power state), but if power states are controlled via power resources, we should execute _ON method of power resource, assigned for desired state AND _OFF method of power resource, assigned for the current power state, so we cannot just ignore the current device power state. Regards. Konstantin. >-----Original Message----- >From: linux-acpi-owner@xxxxxxxxxxxxxxx [mailto:linux-acpi- >owner@xxxxxxxxxxxxxxx] On Behalf Of Bjorn Helgaas >Sent: Tuesday, January 16, 2007 7:54 PM >To: Karasyov, Konstantin A >Cc: Alexey Starikovskiy; Matthew Brett; Salatiel Filho; linux- >acpi@xxxxxxxxxxxxxxx >Subject: Re: PROBLEM: CPU fan shuts down on load of fan.ko in kernel 2.6.18 >and later > >On Monday 15 January 2007 06:33, Karasyov, Konstantin A wrote: >> The fan device FAN1 defines object FN01 as its power resource. _STA >> method of FN01 always return 0x01, i.e. resource is on. So the fan >> driver is unable to turn the fan on, because it thinks that it is >> already in that state. > >The code looks like this: > > int acpi_bus_set_power(acpi_handle handle, int state) > { > ... > if (!device->flags.force_power_state) { > if (device->power.state == ACPI_STATE_UNKNOWN) > acpi_bus_get_power(device->handle, &device->power.state) > if (state == device->power.state) { > return 0; /* already at desired state */ > } > ... > acpi_power_transition(device, state); > >Why do we bother with the "acpi_bus_get_power" at all? The problem >Matthew is seeing wouldn't happen at all if we just deleted everything >in the force_power_state block. > >Then we could execute _ON, _PS0, etc for a device that is already on. >Does that cause bad things to happen? I assume the fan probably works >as desired under Windows, so they probably do something like this. > >Bjorn > >- >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 - 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
