Re: [ACPI] _PDC method in DSDT

Dominik Brodowski
2003-06-23T13:38:34Z

On Mon, Jun 23, 2003 at 02:19:27AM -0700, Grover, Andrew wrote:
> The spec intended FixedFunctionalHW registers to be an "escape hatch".
> FFH means that while ACPI is used for perf state enumeration, the
> transitions will be handled in a CPU-specific driver, not via methods
> described in the ACPI spec. This division (use ACPI for enum, x for
> control) isn't currently supported by cpufreq; ACPI either does both
> enum and control, or neither.

But it could easily be added to the cpufreq drivers. For example, the
speedstep-centrino driver could call a

int acpi_get_frequency_table(struct cpufreq_frequency_table **freq_table)

which returns an array with the frequency in freq_table[i].frequency, and
some sort of "index" in freq_table[i].index, e.g. what needs to be written
into the IA32_PERF_CTL MSR.

Dominik