The reference driver polled but mentioned it was possible to sleep for a computed period to know when it's ready to read. However, polling is quick and works. This also improves responsiveness from the driver.
Testing: tested on ast2400 on quanta-q71l Signed-off-by: Patrick Venture <[email protected]> --- drivers/hwmon/aspeed-pwm-tacho.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-tacho.c index b2ab5612d8a4..a31d2648fb3a 100644 --- a/drivers/hwmon/aspeed-pwm-tacho.c +++ b/drivers/hwmon/aspeed-pwm-tacho.c @@ -163,6 +163,9 @@ #define M_TACH_UNIT 0x00c0 #define INIT_FAN_CTRL 0xFF +/* How many times we poll the fan_tach controller for rpm data. */ +#define FAN_TACH_RPM_TIMEOUT 25 + struct aspeed_pwm_tacho_data { struct regmap *regmap; unsigned long clk_freq; @@ -508,7 +511,7 @@ static u32 aspeed_get_fan_tach_ch_measure_period(struct aspeed_pwm_tacho_data static int aspeed_get_fan_tach_ch_rpm(struct aspeed_pwm_tacho_data *priv, u8 fan_tach_ch) { - u32 raw_data, tach_div, clk_source, sec, val; + u32 raw_data, tach_div, clk_source, sec, val, timeout; u8 fan_tach_ch_source, type, mode, both; regmap_write(priv->regmap, ASPEED_PTCR_TRIGGER, 0); @@ -517,12 +520,20 @@ static int aspeed_get_fan_tach_ch_rpm(struct aspeed_pwm_tacho_data *priv, fan_tach_ch_source = priv->fan_tach_ch_source[fan_tach_ch]; type = priv->pwm_port_type[fan_tach_ch_source]; - sec = (1000 / aspeed_get_fan_tach_ch_measure_period(priv, type)); - msleep(sec); - regmap_read(priv->regmap, ASPEED_PTCR_RESULT, &val); - if (!(val & RESULT_STATUS_MASK)) - return -ETIMEDOUT; + /* + * Instead of sleeping first, poll register for result. + * This is based on the reference driver's approach which expects to + * receive a value quickly. + */ + timeout = 0; + while (!(val & RESULT_STATUS_MASK)) { + timeout++; + if (timeout > FAN_TACH_RPM_TIMEOUT) + return -ETIMEDOUT; + + regmap_read(priv->regmap, ASPEED_PTCR_RESULT, &val); + } raw_data = val & RESULT_VALUE_MASK; tach_div = priv->type_fan_tach_clock_division[type]; -- 2.13.1.611.g7e3b11ae1-goog -- To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
