intel_pstate: Fix BYT frequency reporting

commit b27580b05e6f5253228debc60b8ff4a786ff573a upstream.

BYT has a different conversion from P state to frequency than the core
processors.  This causes the min/max and current frequency to be
misreported on some BYT SKUs. Tested on BYT N2820, Ivybridge and
Haswell processors.

Link: https://bugzilla.yoctoproject.org/show_bug.cgi?id=6663
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 7ab0d9b..ecd8310 100644 (file)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -67,6 +67,7 @@ struct pstate_data {
        int     current_pstate;
        int     min_pstate;
        int     max_pstate;
+       int     scaling;
        int     turbo_pstate;
 };
 
@@ -118,6 +119,7 @@ struct pstate_funcs {
        int (*get_max)(void);
        int (*get_min)(void);
        int (*get_turbo)(void);
+       int (*get_scaling)(void);
        void (*set)(struct cpudata*, int pstate);
        void (*get_vid)(struct cpudata *);
 };
@@ -407,6 +409,22 @@ static void byt_set_pstate(struct cpudata *cpudata, int pstate)
        wrmsrl(MSR_IA32_PERF_CTL, val);
 }
 
+#define BYT_BCLK_FREQS 5
+static int byt_freq_table[BYT_BCLK_FREQS] = { 833, 1000, 1333, 1167, 800};
+
+static int byt_get_scaling(void)
+{
+       u64 value;
+       int i;
+
+       rdmsrl(MSR_FSB_FREQ, value);
+       i = value & 0x3;
+
+       BUG_ON(i > BYT_BCLK_FREQS);
+
+       return byt_freq_table[i] * 100;
+}
+
 static void byt_get_vid(struct cpudata *cpudata)
 {
        u64 value;
@@ -451,6 +469,11 @@ static int core_get_turbo_pstate(void)
        return ret;
 }
 
+static inline int core_get_scaling(void)
+{
+       return 100000;
+}
+
 static void core_set_pstate(struct cpudata *cpudata, int pstate)
 {
        u64 val;
@@ -475,6 +498,7 @@ static struct cpu_defaults core_params = {
                .get_max = core_get_max_pstate,
                .get_min = core_get_min_pstate,
                .get_turbo = core_get_turbo_pstate,
+               .get_scaling = core_get_scaling,
                .set = core_set_pstate,
        },
 };
@@ -493,6 +517,7 @@ static struct cpu_defaults byt_params = {
                .get_min = byt_get_min_pstate,
                .get_turbo = byt_get_turbo_pstate,
                .set = byt_set_pstate,
+               .get_scaling = byt_get_scaling,
                .get_vid = byt_get_vid,
        },
 };
@@ -526,7 +551,7 @@ static void intel_pstate_set_pstate(struct cpudata *cpu, int pstate)
        if (pstate == cpu->pstate.current_pstate)
                return;
 
-       trace_cpu_frequency(pstate * 100000, cpu->cpu);
+       trace_cpu_frequency(pstate * cpu->pstate.scaling, cpu->cpu);
 
        cpu->pstate.current_pstate = pstate;
 
@@ -555,6 +580,7 @@ static void intel_pstate_get_cpu_pstates(struct cpudata *cpu)
        cpu->pstate.min_pstate = pstate_funcs.get_min();
        cpu->pstate.max_pstate = pstate_funcs.get_max();
        cpu->pstate.turbo_pstate = pstate_funcs.get_turbo();
+       cpu->pstate.scaling = pstate_funcs.get_scaling();
 
        if (pstate_funcs.get_vid)
                pstate_funcs.get_vid(cpu);
@@ -574,7 +600,9 @@ static inline void intel_pstate_calc_busy(struct cpudata *cpu,
                core_pct += 1;
 
        sample->freq = fp_toint(
-               mul_fp(int_tofp(cpu->pstate.max_pstate * 1000), core_pct));
+               mul_fp(int_tofp(
+                       cpu->pstate.max_pstate * cpu->pstate.scaling / 100),
+                       core_pct));
 
        sample->core_pct_busy = (int32_t)core_pct;
 }
@@ -817,12 +845,13 @@ static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
        else
                policy->policy = CPUFREQ_POLICY_POWERSAVE;
 
-       policy->min = cpu->pstate.min_pstate * 100000;
-       policy->max = cpu->pstate.turbo_pstate * 100000;
+       policy->min = cpu->pstate.min_pstate * cpu->pstate.scaling;
+       policy->max = cpu->pstate.turbo_pstate * cpu->pstate.scaling;
 
        /* cpuinfo and default policy values */
-       policy->cpuinfo.min_freq = cpu->pstate.min_pstate * 100000;
-       policy->cpuinfo.max_freq = cpu->pstate.turbo_pstate * 100000;
+       policy->cpuinfo.min_freq = cpu->pstate.min_pstate * cpu->pstate.scaling;
+       policy->cpuinfo.max_freq =
+               cpu->pstate.turbo_pstate * cpu->pstate.scaling;
        policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
        cpumask_set_cpu(policy->cpu, policy->cpus);
 
@@ -880,6 +909,7 @@ static void copy_cpu_funcs(struct pstate_funcs *funcs)
        pstate_funcs.get_max   = funcs->get_max;
        pstate_funcs.get_min   = funcs->get_min;
        pstate_funcs.get_turbo = funcs->get_turbo;
+       pstate_funcs.get_scaling = funcs->get_scaling;
        pstate_funcs.set       = funcs->set;
        pstate_funcs.get_vid   = funcs->get_vid;
 }