cpufreq: tegra194: get consistent cpuinfo_cur_freq

Frequency returned by 'cpuinfo_cur_freq' using counters is not fixed
and keeps changing slightly. This change returns a consistent value
from freq_table. If the reconstructed frequency has acceptable delta
from the last written value, then return the frequency corresponding
to the last written ndiv value from freq_table. Otherwise, print a
warning and return the reconstructed freq.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
index e1d931c..7901587 100644 (file)
--- a/drivers/cpufreq/tegra194-cpufreq.c
+++ b/drivers/cpufreq/tegra194-cpufreq.c
@@ -180,9 +180,61 @@ static unsigned int tegra194_get_speed_common(u32 cpu, u32 delay)
        return (rate_mhz * KHZ); /* in KHz */
 }
 
+static void get_cpu_ndiv(void *ndiv)
+{
+       u64 ndiv_val;
+
+       asm volatile("mrs %0, s3_0_c15_c0_4" : "=r" (ndiv_val) : );
+
+       *(u64 *)ndiv = ndiv_val;
+}
+
+static void set_cpu_ndiv(void *data)
+{
+       struct cpufreq_frequency_table *tbl = data;
+       u64 ndiv_val = (u64)tbl->driver_data;
+
+       asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
+}
+
 static unsigned int tegra194_get_speed(u32 cpu)
 {
-       return tegra194_get_speed_common(cpu, US_DELAY);
+       struct tegra194_cpufreq_data *data = cpufreq_get_driver_data();
+       struct cpufreq_frequency_table *pos;
+       unsigned int rate;
+       u64 ndiv;
+       int ret;
+       u32 cl;
+
+       smp_call_function_single(cpu, get_cpu_cluster, &cl, true);
+
+       /* reconstruct actual cpu freq using counters */
+       rate = tegra194_get_speed_common(cpu, US_DELAY);
+
+       /* get last written ndiv value */
+       ret = smp_call_function_single(cpu, get_cpu_ndiv, &ndiv, true);
+       if (WARN_ON_ONCE(ret))
+               return rate;
+
+       /*
+        * If the reconstructed frequency has acceptable delta from
+        * the last written value, then return freq corresponding
+        * to the last written ndiv value from freq_table. This is
+        * done to return consistent value.
+        */
+       cpufreq_for_each_valid_entry(pos, data->tables[cl]) {
+               if (pos->driver_data != ndiv)
+                       continue;
+
+               if (abs(pos->frequency - rate) > 115200) {
+                       pr_warn("cpufreq: cpu%d,cur:%u,set:%u,set ndiv:%llu\n",
+                               cpu, rate, pos->frequency, ndiv);
+               } else {
+                       rate = pos->frequency;
+               }
+               break;
+       }
+       return rate;
 }
 
 static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
@@ -209,14 +261,6 @@ static int tegra194_cpufreq_init(struct cpufreq_policy *policy)
        return 0;
 }
 
-static void set_cpu_ndiv(void *data)
-{
-       struct cpufreq_frequency_table *tbl = data;
-       u64 ndiv_val = (u64)tbl->driver_data;
-
-       asm volatile("msr s3_0_c15_c0_4, %0" : : "r" (ndiv_val));
-}
-
 static int tegra194_cpufreq_set_target(struct cpufreq_policy *policy,
                                       unsigned int index)
 {