From 2f23e319b133c7392493e77f515a237c8e1e6dd6 Mon Sep 17 00:00:00 2001 From: Pascal Paillet Date: Fri, 10 Jan 2020 11:16:05 +0100 Subject: [PATCH] thermal: stm32: Fix low threshold interrupt flood With the STM32 thermal peripheral, it is not possible to dump the temperature that has caused the interrupt. When the temperature reaches the low threshold, we generally read a temperature that is a little bit higher than the low threshold. This maybe due to sampling precision, and also because the CPU becomes hotter when it quits WFI mode. In that case, the framework does not change the trip points. This leads to a lot of low threshold interrupts. The fix is to set the low threshold value 0.5 degrees Celsius below the actual request. The problem is not so frequent with the high threshold and it would no be a good idea to set the threshold value higher than the request. Signed-off-by: Pascal Paillet Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20200110101605.24984-7-p.paillet@st.com --- drivers/thermal/st/stm_thermal.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/thermal/st/stm_thermal.c b/drivers/thermal/st/stm_thermal.c index aaf25ca2f118..1cc5e6c5709e 100644 --- a/drivers/thermal/st/stm_thermal.c +++ b/drivers/thermal/st/stm_thermal.c @@ -321,7 +321,8 @@ static int stm_thermal_set_trips(void *data, int low, int high) if (low > -INT_MAX) { sensor->low_temp_enabled = 1; - ret = stm_thermal_calculate_threshold(sensor, low, &th); + /* add 0.5 of hysteresis due to measurement error */ + ret = stm_thermal_calculate_threshold(sensor, low - 500, &th); if (ret) return ret;