On Fri, Jun 17, 2011 at 03:50:55PM -0400, Matthew Garrett wrote:
> Some AMD systems may round the frequencies in ACPI tables to 100MHz
> boundaries. We can obtain the real frequencies from MSRs, so add a quirk
> to fix these frequencies up on AMD systems.
>
> Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
> ---
> drivers/acpi/processor_perflib.c | 30 ++++++++++++++++++++++++++++++
> 1 files changed, 30 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
> index 85b3237..9e18173 100644
> --- a/drivers/acpi/processor_perflib.c
> +++ b/drivers/acpi/processor_perflib.c
> @@ -302,6 +302,34 @@ static int acpi_processor_get_performance_control(struct acpi_processor *pr)
> return result;
> }
>
> +#ifdef CONFIG_X86
> +/*
> + * Some AMDs have 50MHz frequency multiples, but only provide 100MHz rounding
> + * in their ACPI data. Calculate the real values and fix up the _PSS data.
> + */
> +static void amd_fixup_frequency(struct acpi_processor_px *px, int i)
> +{
> + u32 hi, lo, fid, did;
> + int index = px->control & 0x00000007;
> +
> + if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
> + return;
> +
> + if ((boot_cpu_data.x86 == 0x10 && boot_cpu_data.x86_model < 10)
> + || boot_cpu_data.x86 == 0x11) {
> + rdmsr(0xc0010064 + index, lo, hi);
MSR_PSTATE_DEF_BASE
> + fid = lo & 0x3f;
> + did = (lo >> 6) & 7;
> + if (boot_cpu_data.x86 == 0x10)
> + px->core_frequency = (100 * (fid + 0x10)) >> did;
> + else
> + px->core_frequency = (100 * (fid + 8)) >> did;
> + }
> +}
> +#else
> +static void amd_fixup_frequency(struct acpi_processor_px *px, int i) {};
> +#endif
> +
> static int acpi_processor_get_performance_states(struct acpi_processor *pr)
> {
> int result = 0;
> @@ -356,6 +384,8 @@ static int acpi_processor_get_performance_states(struct acpi_processor *pr)
> goto end;
> }
>
> + amd_fixup_frequency(px, i);
> +
> ACPI_DEBUG_PRINT((ACPI_DB_INFO,
> "State [%d]: core_frequency[%d] power[%d] transition_latency[%d] bus_master_latency[%d] control[0x%x] status[0x%x]\n",
> i,
> --
> 1.7.5.2
>
> --
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--
Regards/Gruss,
Boris.
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