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   1 From 681b652c9dfc4037d4a55b2733e091a4e1a5de18 Mon Sep 17 00:00:00 2001
   2 From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
   3 Date: Wed, 19 Apr 2023 08:11:46 +0200
   4 Subject: [PATCH 17/42] thermal/drivers/mediatek: Add temperature constraints
   5  to validate read
   6 MIME-Version: 1.0
   7 Content-Type: text/plain; charset=UTF-8
   8 Content-Transfer-Encoding: 8bit
   9
  10 The AUXADC thermal v1 allows reading temperature range between -20°C to
  11 150°C and any value out of this range is invalid.
  12
  13 Add new definitions for MT8173_TEMP_{MIN_MAX} and a new small helper
  14 mtk_thermal_temp_is_valid() to check if new readings are in range: if
  15 not, we tell to the API that the reading is invalid by returning
  16 THERMAL_TEMP_INVALID.
  17
  18 It was chosen to introduce the helper function because, even though this
  19 temperature range is realistically ok for all, it comes from a downstream
  20 kernel driver for version 1, but here we also support v2 and v3 which may
  21 may have wider constraints.
  22
  23 Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
  24 Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
  25 Link: https://lore.kernel.org/r/20230419061146.22246-3-angelogioacchino.delregno@collabora.com
  26 ---
  27  drivers/thermal/mediatek/auxadc_thermal.c | 24 +++++++++++++++++------
  28  1 file changed, 18 insertions(+), 6 deletions(-)
  29
  30 --- a/drivers/thermal/mediatek/auxadc_thermal.c
  31 +++ b/drivers/thermal/mediatek/auxadc_thermal.c
  32 @@ -116,6 +116,10 @@
  33  /* The calibration coefficient of sensor  */
  34  #define MT8173_CALIBRATION     165
  35
  36 +/* Valid temperatures range */
  37 +#define MT8173_TEMP_MIN                -20000
  38 +#define MT8173_TEMP_MAX                150000
  39 +
  40  /*
  41   * Layout of the fuses providing the calibration data
  42   * These macros could be used for MT8183, MT8173, MT2701, and MT2712.
  43 @@ -689,6 +693,11 @@ static const struct mtk_thermal_data mt7
  44         .version = MTK_THERMAL_V3,
  45  };
  46
  47 +static bool mtk_thermal_temp_is_valid(int temp)
  48 +{
  49 +       return (temp >= MT8173_TEMP_MIN) && (temp <= MT8173_TEMP_MAX);
  50 +}
  51 +
  52  /**
  53   * raw_to_mcelsius_v1 - convert a raw ADC value to mcelsius
  54   * @mt:        The thermal controller
  55 @@ -815,14 +824,17 @@ static int mtk_thermal_bank_temperature(
  56                 temp = mt->raw_to_mcelsius(
  57                         mt, conf->bank_data[bank->id].sensors[i], raw);
  58
  59 -
  60                 /*
  61 -                * The first read of a sensor often contains very high bogus
  62 -                * temperature value. Filter these out so that the system does
  63 -                * not immediately shut down.
  64 +                * Depending on the filt/sen intervals and ADC polling time,
  65 +                * we may need up to 60 milliseconds after initialization: this
  66 +                * will result in the first reading containing an out of range
  67 +                * temperature value.
  68 +                * Validate the reading to both address the aforementioned issue
  69 +                * and to eventually avoid bogus readings during runtime in the
  70 +                * event that the AUXADC gets unstable due to high EMI, etc.
  71                  */
  72 -               if (temp > 200000)
  73 -                       temp = 0;
  74 +               if (!mtk_thermal_temp_is_valid(temp))
  75 +                       temp = THERMAL_TEMP_INVALID;
  76
  77                 if (temp > max)
  78                         max = temp;