From d0771f4995d3285756bf496cf6e346df99481f83 Mon Sep 17 00:00:00 2001 From: James Calligeros Date: Sun, 3 May 2026 22:23:24 +1000 Subject: ASoC: tas2770: Deal with bogus initial temperature value TAS2770 initialises the temperature readout registers to 0. This value persists until the chip is fully powered up and the ADC starts sampling. The ADC then persists the last sampled temperature during software shutdown. The ADC should therefore never return 0 in normal operating conditions, so return -ENODATA and mark it as a fault condition using HWMON_T_FAULT. Fixes: ff73e2780169 ("ASoC: tas2770: expose die temp to hwmon") Signed-off-by: James Calligeros Signed-off-by: Mark Brown --- sound/soc/codecs/tas2770.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/sound/soc/codecs/tas2770.c b/sound/soc/codecs/tas2770.c index 50501bcbe916..dbda9f327535 100644 --- a/sound/soc/codecs/tas2770.c +++ b/sound/soc/codecs/tas2770.c @@ -633,10 +633,27 @@ static int tas2770_read_die_temp(struct tas2770_priv *tas2770, long *result) * value read back from its registers will be the last value sampled * before entering software shutdown. */ + if (reading == 0) + return -ENODATA; + *result = (reading - (93 * 16)) * 1000 / 16; return 0; } +static int tas2770_hwmon_is_fault(struct tas2770_priv *tas2770, long *result) +{ + int ret; + long temp; + + ret = tas2770_read_die_temp(tas2770, &temp); + if (ret == -ENODATA) { + *result = true; + return 0; + } + + return ret; +} + static umode_t tas2770_hwmon_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr, int channel) @@ -646,6 +663,7 @@ static umode_t tas2770_hwmon_is_visible(const void *data, switch (attr) { case hwmon_temp_input: + case hwmon_temp_fault: return 0444; default: break; @@ -665,6 +683,9 @@ static int tas2770_hwmon_read(struct device *dev, case hwmon_temp_input: ret = tas2770_read_die_temp(tas2770, val); break; + case hwmon_temp_fault: + ret = tas2770_hwmon_is_fault(tas2770, val); + break; default: ret = -EOPNOTSUPP; break; @@ -674,7 +695,7 @@ static int tas2770_hwmon_read(struct device *dev, } static const struct hwmon_channel_info *const tas2770_hwmon_info[] = { - HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT), + HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_FAULT), NULL }; -- cgit v1.2.3