The controller should provide an answer nearly immediately if the
fan_tach period is short. I found through testing that the combination
of these factors improved the device driver responsiveness.
Testing: tested on quanta-q71l board with aspeed ast2400.
Signed-off-by: Patrick Venture <venture@xxxxxxxxxx>
---
drivers/hwmon/aspeed-pwm-tacho.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-tacho.c
index 86e2ea8287a7..9559c7b7e8c7 100644
--- a/drivers/hwmon/aspeed-pwm-tacho.c
+++ b/drivers/hwmon/aspeed-pwm-tacho.c
@@ -509,6 +509,7 @@ 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 timeout = 0;
u8 fan_tach_ch_source, type, mode, both;
regmap_write(priv->regmap, ASPEED_PTCR_TRIGGER, 0);
@@ -517,12 +518,17 @@ 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.
+ */
+ while (!(val & RESULT_STATUS_MASK)) {
+ timeout++;
+ if (timeout > 25)
+ return -ETIMEDOUT;
+ }
raw_data = val & RESULT_VALUE_MASK;
tach_div = priv->type_fan_tach_clock_division[type];
--
2.13.1.611.g7e3b11ae1-goog
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