On Monday 02 July 2007, Rafael J. Wysocki wrote: > On Monday, 2 July 2007 07:49, David Brownell wrote: > > Also, recall that this was originally PCI-specific. A generalized > > approach would return a range of states, not a single state that > > embeds a particular policy that may not be universally appropriate... > > Via pointers and the return value equal to 0 on success? It could as easily be one pointer: "int minmax[2]". Then min == minmax[0] and max == minmax[1], and the ACPI calls could write the caller's data directly. But in general, yes -- pointer, not single return value. > > The logic was that PCI devices can all support PCI_D0 and PCI_D3. > > For non-PCI devices we can't actually know that. So "min" should > > probably default to ACPI_STATE_D0. If this returns a range, then > > such issues can stay out of this code. > > The ACPI spec says that all devices must support D0 and D3. ISTR that it actually says they must "recognize" D3. That's not the same as actually implementing a software controllable power-off state ... and not the same as imposing a "use the biggest numbered D-state" policy at this level. > > > + /* > > > + * If _PRW says we can wake from the upcoming system state, the _SxD > > > + * value can wake ... and we'll assume a wakeup-aware driver. If _SxW > > > + * methods exist (ACPI 3.x), they give the lowest power D-state that > > > + * can also wake the system. _S0W can be valid. > > > + */ > > > + if (acpi_target_sleep_state == ACPI_STATE_S0 || > > > + (dev->wakeup.state.enabled && > > > > This used device_may_wakeup() before. That ACPI flag is not a > > direct analogue ... without looking again at the issues, I'd > > say the right solution is to phase out the ACPI-only flags in > > new code. > > Hm, I'm not sure. This is an ACPI routine after all ... It's in the Linux kernel, talking about Linux devices. Some of them have ACPI support; many don't. (Like the USB device nodes, and anything else layered on top of mainboard devices.) > > Maybe just expect the caller to pass the results > > of device_may_wakeup() in ... or update the signature to accept > > a "struct device", and fetch the handle from there. (That'd > > be a better match for most callers, I'd think...) > > In that case it would be nicer to pass 'struct acpi_device *' rahter than > 'struct device *', IMO. I'll disagree. Outside of the ACPI code, virtually nothing has any reason to see an "acpi_device" ... but virtually everything has reason to see a "device". Even ACPI code can rely on there being a "device" inside "acpi_device"! This touches on a different problem. The ACPI device tree is parallel to the "real" tree. In the cases there's a one-to-one correspondence, there's no confusion; any acpi_device corresponds to one "real" device, and vice versa. BUT ... there are cases where the correspondence isn't one-to-one. Those cases need to be addressed, by moving towards a one-to-one correspondence. Cases like PCI bridges can be easily dealt with now, given some resequencing of init logic: use the PNP node instead of faking out a toplevel /sys/devices/pci0000:00 node. But things like PS2 keyboard and mouse nodes are funkier. - Dave _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
