linux-kernel - Re: [PATCH V2 4/6] ACPI: Add fixups for AMD P-state figures

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Date:	Sat, 18 Jun 2011 13:28:25 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Matthew Garrett <mjg@...hat.com>
Cc:	linux-kernel@...r.kernel.org, borislav.petkov@....com,
	davej@...hat.com, mark.langsdorf@....com, cpufreq@...r.kernel.org,
	andreas.herrmann3@....com
Subject: Re: [PATCH V2 4/6] ACPI: Add fixups for AMD P-state figures

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@...hat.com>
> ---
>  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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