on 12/09/2010 19:00 Alexander Motin said the following: > > I am not sure this patch is complete:
Well, I agree, it's far from complete. And situation is somewhat messy. > 1) AFAIR I have seen somewhere example where system had several C-states > with different latency, but the same type - C3. Type only means > enter/exit semantics, and there could be several states with the same > semantics. Not sire how to properly them in this case. ACPI specification suggests how to address this, but I am not sure if we want to follow that suggestion and how we would do that: ACPI> Notice in the example above that OSPM should anticipate the possibility of a _CST object providing more ACPI> than one entry with the same C_State_Type value. In this case OSPM must decide which C_State_Register ACPI> it will use to enter that C state. So it looks like the specification does tie C_State_Type to "C state". But then, in general, the specification looks confusing. It mentions C4, ..., Cn states; but then says that their enter/exit semantics should correspond to C1, C2, C3; but then it uses "1, 2, 3, *etc*" [emphasis mine] when it describes C State type. So, at least I am confused as to what they would designate with C4 - a state described in _CST with type of 4, or a forth state in _CST perhaps with a type of 3. And entry/exit semantics the state would have in the former case. I do not see an explicit answer in their wording. > May be existing > approach was not so bad. It is ACPI C-states, not CPU C-states, they are > not same. > May be we should just mention type somewhere in addition. > 2) This change makes heavily understandable values of cx_lowest. > 3) If touch cx_lowest, I would prefer to see there possibility to set it > to some abstract C6 or whatever, allowing system automatically choose > state it has available at the moment. > Yes, I agree. It's just overall confusing. But you are correct that index of a C-state works better than "C-state-type" or whatever it can be called. And a user probably doesn't care much about the latter. But probably it's a good idea to report the type somewhere. I am also going to take a look how Linux and OpenSolaris name the C-states. -- Andriy Gapon _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-acpi To unsubscribe, send any mail to "[email protected]"
