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thermal: rockchip: rk3288: fix temperature-jump issue

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Due to 32k clock jitter, tsadc will wrongly report a very
high temperature, that is a temperature-jump. This may lead
to an abnormal OS reboot. A filter function is added to
predict the true temperature.

Change-Id: I5b5641efe8e64b4058a604f274350b1e94584fa6
Signed-off-by: Rocky Hao <rocky.hao@rock-chips.com>
Signed-off-by: Elaine Zhang <zhangqing@rock-chips.com>
This commit is contained in:
Rocky Hao
2017-09-01 16:43:38 +08:00
committed by Tao Huang
parent e4a125baaf
commit e75915eb34
1 changed files with 86 additions and 1 deletions
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87
drivers/thermal/rockchip_thermal.c
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@@ -227,6 +227,15 @@ struct rockchip_thermal_data {
#define GRF_TSADC_VCM_EN_L (0x10001 << 7)
#define GRF_TSADC_VCM_EN_H (0x10001 << 7)
#define MIN_TEMP (-40000)
#define MAX_TEMP (125000)
#define BASE (1024)
#define BASE_SHIFT (10)
#define START_DEBOUNCE_COUNT (100)
#define HIGHER_DEBOUNCE_TEMP (30)
#define LOWER_DEBOUNCE_TEMP (15)
/**
* struct tsadc_table - code to temperature conversion table
* @code: the value of adc channel
@@ -748,6 +757,82 @@ static int rk_tsadcv2_get_temp(const struct chip_tsadc_table *table,
return rk_tsadcv2_code_to_temp(table, val, temp);
}
static int predict_temp(int temp)
{
/*
* The deviation of prediction. the temperature will not change rapidly,
* so this cov_q is small
*/
int cov_q = 18;
/*
* The deviation of tsadc's reading, deviation of tsadc is very big when
* abnormal temperature is get
*/
int cov_r = 542;
int gain;
int temp_mid;
int temp_now;
int prob_mid;
int prob_now;
static int temp_last = 25;
static int prob_last = 20;
static int bounding_cnt;
/*
* Before START_DEBOUNCE_COUNT's samples of temperature, we consider
* tsadc is stable, i.e. after that, the temperature may be not stable
* and may have abnormal reading, so we set a bounding temperature. If
* the reading from tsadc is too big, we set the delta temperature of
* DEBOUNCE_TEMP/3 comparing to the last temperature.
*/
if (bounding_cnt++ > START_DEBOUNCE_COUNT) {
bounding_cnt = START_DEBOUNCE_COUNT;
if (temp - temp_last > HIGHER_DEBOUNCE_TEMP)
temp = temp_last + HIGHER_DEBOUNCE_TEMP / 3;
if (temp_last - temp > LOWER_DEBOUNCE_TEMP)
temp = temp_last - LOWER_DEBOUNCE_TEMP / 3;
}
temp_mid = temp_last;
/* calculate the probability of this time's prediction */
prob_mid = prob_last + cov_q;
/* calculate the Kalman Gain */
gain = (prob_mid * BASE) / (prob_mid + cov_r);
/* calculate the prediction of temperature */
temp_now = temp_mid + (gain * (temp - temp_mid) >> BASE_SHIFT);
/*
* Base on this time's Kalman Gain, ajust our probability of prediction
* for next time calculation
*/
prob_now = ((BASE - gain) * prob_mid) >> BASE_SHIFT;
prob_last = prob_now;
temp_last = temp_now;
return temp_last;
}
static int rk_tsadcv3_get_temp(const struct chip_tsadc_table *table,
int chn, void __iomem *regs, int *temp)
{
u32 val;
int ret;
val = readl_relaxed(regs + TSADCV2_DATA(chn));
ret = rk_tsadcv2_code_to_temp(table, val, temp);
if (!ret)
*temp = predict_temp(*temp);
return ret;
}
static int rk_tsadcv2_alarm_temp(const struct chip_tsadc_table *table,
int chn, void __iomem *regs, int temp)
{
@@ -878,7 +963,7 @@ static const struct rockchip_tsadc_chip rk3288_tsadc_data = {
.initialize = rk_tsadcv2_initialize,
.irq_ack = rk_tsadcv2_irq_ack,
.control = rk_tsadcv2_control,
.get_temp = rk_tsadcv2_get_temp,
.get_temp = rk_tsadcv3_get_temp,
.set_alarm_temp = rk_tsadcv2_alarm_temp,
.set_tshut_temp = rk_tsadcv2_tshut_temp,
.set_tshut_mode = rk_tsadcv2_tshut_mode,