target/linux/ipq40xx/patches-4.14/081-clk-fix-apss-cpu-overclocking.patch

   1 From f2b87dc1028b710ec8ce25808b9d21f92b376184 Mon Sep 17 00:00:00 2001
   2 From: Christian Lamparter <chunkeey@googlemail.com>
   3 Date: Sun, 11 Mar 2018 14:41:31 +0100
   4 Subject: [PATCH 2/2] clk: fix apss cpu overclocking
   5
   6 There's an interaction issue between the clk changes:"
   7 clk: qcom: ipq4019: Add the apss cpu pll divider clock node
   8 clk: qcom: ipq4019: remove fixed clocks and add pll clocks
   9 " and the cpufreq-dt.
  10
  11 cpufreq-dt is now spamming the kernel-log with the following:
  12
  13 [ 1099.190658] cpu cpu0: dev_pm_opp_set_rate: failed to find current OPP
  14 for freq 761142857 (-34)
  15
  16 This only happens on certain devices like the Compex WPJ428
  17 and AVM FritzBox!4040. However, other devices like the Asus
  18 RT-AC58U and Meraki MR33 work just fine.
  19
  20 The issue stem from the fact that all higher CPU-Clocks
  21 are achieved by switching the clock-parent to the P_DDRPLLAPSS
  22 (ddrpllapss). Which is set by Qualcomm's proprietary bootcode
  23 as part of the DDR calibration.
  24
  25 For example, the FB4040 uses 256 MiB Nanya NT5CC128M16IP clocked
  26 at round 533 MHz (ddrpllsdcc = 190285714 Hz).
  27
  28 whereas the 128 MiB Nanya NT5CC64M16GP-DI in the ASUS RT-AC58U is
  29 clocked at a slightly higher 537 MHz ( ddrpllsdcc = 192000000 Hz).
  30
  31 This patch attempts to fix the issue by modifying
  32 clk_cpu_div_round_rate(), clk_cpu_div_set_rate(), clk_cpu_div_recalc_rate()
  33 to use a new qcom_find_freq_close() function, which returns the closest
  34 matching frequency, instead of the next higher. This way, the SoC in
  35 the FB4040 (with its max clock speed of 710.4 MHz) will no longer
  36 try to overclock to 761 MHz.
  37
  38 Fixes: d83dcacea18 ("clk: qcom: ipq4019: Add the apss cpu pll divider clock node")
  39 Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
  40 Signed-off-by: John Crispin <john@phrozen.org>
  41 ---
  42  drivers/clk/qcom/gcc-ipq4019.c | 34 +++++++++++++++++++++++++++++++---
  43  1 file changed, 31 insertions(+), 3 deletions(-)
  44
  45 diff --git a/drivers/clk/qcom/gcc-ipq4019.c b/drivers/clk/qcom/gcc-ipq4019.c
  46 index 46cb256b4aa2..4ec43f7d2e52 100644
  47 --- a/drivers/clk/qcom/gcc-ipq4019.c
  48 +++ b/drivers/clk/qcom/gcc-ipq4019.c
  49 @@ -1253,6 +1253,29 @@ static const struct clk_fepll_vco gcc_fepll_vco = {
  50         .reg = 0x2f020,
  51  };
  52
  53 +
  54 +const struct freq_tbl *qcom_find_freq_close(const struct freq_tbl *f,
  55 +                                            unsigned long rate)
  56 +{
  57 +       const struct freq_tbl *last = NULL;
  58 +
  59 +       for ( ; f->freq; f++) {
  60 +               if (rate == f->freq)
  61 +                       return f;
  62 +
  63 +               if (f->freq > rate) {
  64 +                       if (!last ||
  65 +                          (f->freq - rate) < (rate - last->freq))
  66 +                               return f;
  67 +                       else
  68 +                               return last;
  69 +               }
  70 +               last = f;
  71 +       }
  72 +
  73 +       return last;
  74 +}
  75 +
  76  /*
  77   * Round rate function for APSS CPU PLL Clock divider.
  78   * It looks up the frequency table and returns the next higher frequency
  79 @@ -1265,7 +1288,7 @@ static long clk_cpu_div_round_rate(struct clk_hw *hw, unsigned long rate,
  80         struct clk_hw *p_hw;
  81         const struct freq_tbl *f;
  82
  83 -       f = qcom_find_freq(pll->freq_tbl, rate);
  84 +       f = qcom_find_freq_close(pll->freq_tbl, rate);
  85         if (!f)
  86                 return -EINVAL;
  87
  88 @@ -1288,7 +1311,7 @@ static int clk_cpu_div_set_rate(struct clk_hw *hw, unsigned long rate,
  89         u32 mask;
  90         int ret;
  91
  92 -       f = qcom_find_freq(pll->freq_tbl, rate);
  93 +       f = qcom_find_freq_close(pll->freq_tbl, rate);
  94         if (!f)
  95                 return -EINVAL;
  96
  97 @@ -1315,6 +1338,7 @@ static unsigned long
  98  clk_cpu_div_recalc_rate(struct clk_hw *hw,
  99                         unsigned long parent_rate)
 100  {
 101 +       const struct freq_tbl *f;
 102         struct clk_fepll *pll = to_clk_fepll(hw);
 103         u32 cdiv, pre_div;
 104         u64 rate;
 105 @@ -1335,7 +1359,11 @@ clk_cpu_div_recalc_rate(struct clk_hw *hw,
 106         rate = clk_fepll_vco_calc_rate(pll, parent_rate) * 2;
 107         do_div(rate, pre_div);
 108
 109 -       return rate;
 110 +       f = qcom_find_freq_close(pll->freq_tbl, rate);
 111 +       if (!f)
 112 +               return rate;
 113 +
 114 +       return f->freq;
 115  };
 116
 117  static const struct clk_ops clk_regmap_cpu_div_ops = {
 118 --
 119 2.11.0
 120