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