From ca446d06351992e4f1a7c1e5e99870ab4ec5188f Mon Sep 17 00:00:00 2001 From: Andreas Herrmann Date: Wed, 22 Apr 2009 13:48:33 +0200 Subject: [PATCH] [CPUFREQ] powernow-k8: determine exact CPU frequency for HW Pstates Slightly modified by trenn@suse.de -> only do this on fam 10h and fam 11h. Currently powernow-k8 determines CPU frequency from ACPI PSS objects, but according to AMD family 11h BKDG this frequency is just a rounded value: "CoreFreq (MHz) = The CPU COF specified by MSRC001_00[6B:64][CpuFid] rounded to the nearest 100 Mhz." As a consequnce powernow-k8 reports wrong CPU frequency on some systems, e.g. on Turion X2 Ultra: powernow-k8: Found 1 AMD Turion(tm)X2 Ultra DualCore Mobile ZM-82 processors (2 cpu cores) (version 2.20.00) powernow-k8: 0 : pstate 0 (2200 MHz) powernow-k8: 1 : pstate 1 (1100 MHz) powernow-k8: 2 : pstate 2 (600 MHz) But this is wrong as frequency for Pstate2 is 550 MHz. x86info reports it correctly: #x86info -a |grep Pstate ... Pstate-0: fid=e, did=0, vid=24 (2200MHz) Pstate-1: fid=e, did=1, vid=30 (1100MHz) Pstate-2: fid=e, did=2, vid=3c (550MHz) (current) Solution is to determine the frequency directly from Pstate MSRs instead of using rounded values from ACPI table. Signed-off-by: Andreas Herrmann Signed-off-by: Thomas Renninger Signed-off-by: Dave Jones --- arch/x86/kernel/cpu/cpufreq/powernow-k8.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c index feef10c..f6b32d1 100644 --- a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c +++ b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c @@ -649,6 +649,20 @@ static void print_basics(struct powernow_k8_data *data) data->batps); } +static u32 freq_from_fid_did(u32 fid, u32 did) +{ + u32 mhz = 0; + + if (boot_cpu_data.x86 == 0x10) + mhz = (100 * (fid + 0x10)) >> did; + else if (boot_cpu_data.x86 == 0x11) + mhz = (100 * (fid + 8)) >> did; + else + BUG(); + + return mhz * 1000; +} + static int fill_powernow_table(struct powernow_k8_data *data, struct pst_s *pst, u8 maxvid) { @@ -923,8 +937,13 @@ static int fill_powernow_table_pstate(struct powernow_k8_data *data, powernow_table[i].index = index; - powernow_table[i].frequency = - data->acpi_data.states[i].core_frequency * 1000; + /* Frequency may be rounded for these */ + if (boot_cpu_data.x86 == 0x10 || boot_cpu_data.x86 == 0x11) { + powernow_table[i].frequency = + freq_from_fid_did(lo & 0x3f, (lo >> 6) & 7); + } else + powernow_table[i].frequency = + data->acpi_data.states[i].core_frequency * 1000; } return 0; } -- 2.7.4