1 files changed, 18 insertions, 6 deletions

diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-tacho.c
index b2ab5612d8a4..ddfe66bdff86 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 long we sleep in us while waiting for an RPM result. */
+#define ASPEED_RPM_STATUS_SLEEP_USEC    500
+
 struct aspeed_pwm_tacho_data {
         struct regmap *regmap;
         unsigned long clk_freq;
@@ -508,8 +511,9 @@ 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, msec, usec, val;
         u8 fan_tach_ch_source, type, mode, both;
+        int ret;
 
         regmap_write(priv->regmap, ASPEED_PTCR_TRIGGER, 0);
         regmap_write(priv->regmap, ASPEED_PTCR_TRIGGER, 0x1 << fan_tach_ch);
@@ -517,12 +521,20 @@ 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);
+        msec = (1000 / aspeed_get_fan_tach_ch_measure_period(priv, type));
+        usec = msec * 1000;
+
+        ret = regmap_read_poll_timeout(
+                priv->regmap,
+                ASPEED_PTCR_RESULT,
+                val,
+                (val & RESULT_STATUS_MASK),
+                ASPEED_RPM_STATUS_SLEEP_USEC,
+                usec);
 
-        regmap_read(priv->regmap, ASPEED_PTCR_RESULT, &val);
-        if (!(val & RESULT_STATUS_MASK))
-                return -ETIMEDOUT;
+        /* return -ETIMEDOUT if we didn't get an answer. */
+        if (ret)
+                return ret;
 
         raw_data = val & RESULT_VALUE_MASK;
         tach_div = priv->type_fan_tach_clock_division[type];