On 28 November 2013 18:39, Rafael J. Wysocki rjw@rjwysocki.net wrote:
acpi-cpufreq is one at least.
Anyway, this isn't about ACPI or anything like that, but hardware. Generally speaking, on modern Intel hardware the processor itself chooses the frequency to run at and it may do that behind your back. Moreover, it can choose a frequency different from the one you asked for. And it won't choose one that it can't run at for that matter. :-)
Overall, I don't believe that the problem you're trying to address is relevant for any non-exotic x86 hardware.
Okay.. So wouldn't it be better that we add this special flag only when we face a real problem? Otherwise this flag might stay unused for long time and then we might end up removing it..
So there should be a flag for drivers indicating whether or not frequencies (or operation points in general) are directly testable and the check should only be done for the drivers with the flag set.
Probably a flag with properties exactly opposite to what you mentioned, so that we don't need to modify most of the drivers..
That would work too if you prefer it.
In case we need this flag, what should we name it? ALLOW_UNKNOWN_FREQ ??