recipes-kernel/linux/linux-3.0/pm-wip/cpufreq/0019-OMAP2-CPUfreq-update-lpj-with-reference-value-to-avo.patch

   1 From 9b352c30c2ddb0dec7f6597148f22ae5bbc27877 Mon Sep 17 00:00:00 2001
   2 From: Russell King <rmk+kernel@arm.linux.org.uk>
   3 Date: Mon, 11 Jul 2011 23:10:04 +0530
   4 Subject: [PATCH 19/19] OMAP2+: CPUfreq: update lpj with reference value to avoid progressive error.
   5
   6 Adjust _both_ the per-cpu loops_per_jiffy and global lpj. Calibrate them
   7 with with reference to the initial values to avoid a progressively
   8 bigger and bigger error in the value over time.
   9
  10 While at this, re-use the notifiers for UP/SMP since on
  11 UP machine or UP_ON_SMP policy->cpus mask would contain only
  12 the boot CPU.
  13
  14 Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
  15 [santosh.shilimkar@ti.com: re-based against omap cpufreq
  16 upstream branch and fixed notifiers]
  17 Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
  18 Cc: Kevin Hilman <khilman@ti.com>
  19 Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
  20 ---
  21  arch/arm/mach-omap2/omap2plus-cpufreq.c |   50 ++++++++++++++++--------------
  22  1 files changed, 27 insertions(+), 23 deletions(-)
  23
  24 diff --git a/arch/arm/mach-omap2/omap2plus-cpufreq.c b/arch/arm/mach-omap2/omap2plus-cpufreq.c
  25 index 1f3b2e1..de82e87 100644
  26 --- a/arch/arm/mach-omap2/omap2plus-cpufreq.c
  27 +++ b/arch/arm/mach-omap2/omap2plus-cpufreq.c
  28 @@ -38,6 +38,16 @@
  29
  30  #include <mach/hardware.h>
  31
  32 +#ifdef CONFIG_SMP
  33 +struct lpj_info {
  34 +       unsigned long   ref;
  35 +       unsigned int    freq;
  36 +};
  37 +
  38 +static DEFINE_PER_CPU(struct lpj_info, lpj_ref);
  39 +static struct lpj_info global_lpj_ref;
  40 +#endif
  41 +
  42  static struct cpufreq_frequency_table *freq_table;
  43  static atomic_t freq_table_users = ATOMIC_INIT(0);
  44  static struct clk *mpu_clk;
  45 @@ -96,37 +106,18 @@ static int omap_target(struct cpufreq_policy *policy,
  46         if (freqs.old == freqs.new && policy->cur == freqs.new)
  47                 return ret;
  48
  49 -       if (!is_smp()) {
  50 -               cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  51 -               goto set_freq;
  52 -       }
  53 -
  54         /* notifiers */
  55         for_each_cpu(i, policy->cpus) {
  56                 freqs.cpu = i;
  57                 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  58         }
  59
  60 -set_freq:
  61  #ifdef CONFIG_CPU_FREQ_DEBUG
  62         pr_info("cpufreq-omap: transition: %u --> %u\n", freqs.old, freqs.new);
  63  #endif
  64
  65         ret = clk_set_rate(mpu_clk, freqs.new * 1000);
  66 -
  67 -       /*
  68 -        * Generic CPUFREQ driver jiffy update is under !SMP. So jiffies
  69 -        * won't get updated when UP machine cpufreq build with
  70 -        * CONFIG_SMP enabled. Below code is added only to manage that
  71 -        * scenario
  72 -        */
  73         freqs.new = omap_getspeed(policy->cpu);
  74 -       if (!is_smp()) {
  75 -               loops_per_jiffy =
  76 -                        cpufreq_scale(loops_per_jiffy, freqs.old, freqs.new);
  77 -               cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  78 -               goto skip_lpj;
  79 -       }
  80
  81  #ifdef CONFIG_SMP
  82         /*
  83 @@ -134,10 +125,24 @@ set_freq:
  84          * cpufreq driver. So, update the per-CPU loops_per_jiffy value
  85          * on frequency transition. We need to update all dependent CPUs.
  86          */
  87 -       for_each_cpu(i, policy->cpus)
  88 +       for_each_cpu(i, policy->cpus) {
  89 +               struct lpj_info *lpj = &per_cpu(lpj_ref, i);
  90 +               if (!lpj->freq) {
  91 +                       lpj->ref = per_cpu(cpu_data, i).loops_per_jiffy;
  92 +                       lpj->freq = freqs.old;
  93 +               }
  94 +
  95                 per_cpu(cpu_data, i).loops_per_jiffy =
  96 -                       cpufreq_scale(per_cpu(cpu_data, i).loops_per_jiffy,
  97 -                                       freqs.old, freqs.new);
  98 +                       cpufreq_scale(lpj->ref, lpj->freq, freqs.new);
  99 +       }
 100 +
 101 +       /* And don't forget to adjust the global one */
 102 +       if (!global_lpj_ref.freq) {
 103 +               global_lpj_ref.ref = loops_per_jiffy;
 104 +               global_lpj_ref.freq = freqs.old;
 105 +       }
 106 +       loops_per_jiffy = cpufreq_scale(global_lpj_ref.ref, global_lpj_ref.freq,
 107 +                                       freqs.new);
 108  #endif
 109
 110         /* notifiers */
 111 @@ -146,7 +151,6 @@ set_freq:
 112                 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 113         }
 114
 115 -skip_lpj:
 116         return ret;
 117  }
 118
 119 --
 120 1.6.6.1
 121