Re: [PATCH v3] cpufreq: tegra194: get consistent cpuinfo_cur_freq

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Ping.


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@xxxxxxxxxx>
---

Sending only this patch as other patch not required after the change
to convert 'pr_warn' to 'pr_info' in cpufreq core for unlisted freq.
Changelog
v1[2] -> v3:
- Removed unwanted checks for cpu_online and max cluster number
- Used WARN_ON_ONCE to avoid print flooding.

v1[1] -> v2:
- Minor changes to improve comments and reduce debug prints.
- Get freq table from cluster specific data instead of policy.

[2] https://marc.info/?l=linux-tegra&m=160216218511280&w=2
[1] https://marc.info/?l=linux-arm-kernel&m=160028821117535&w=2

  drivers/cpufreq/tegra194-cpufreq.c | 62 ++++++++++++++++++++++++++++++++------
  1 file changed, 53 insertions(+), 9 deletions(-)

diff --git a/drivers/cpufreq/tegra194-cpufreq.c b/drivers/cpufreq/tegra194-cpufreq.c
index e1d931c..7901587 100644
--- 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)
  {
--
2.7.4




[Index of Archives]     [ARM Kernel]     [Linux ARM]     [Linux ARM MSM]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux