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Commit 44b41366 authored by Patrick Venture's avatar Patrick Venture Committed by Guenter Roeck
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hwmon: (aspeed-pwm-tacho) Poll with short sleeps. 



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
with minimal sleeps is quick and works.  This also improves responsiveness
from the driver.

Testing: tested on ast2400 on quanta-q71l

Signed-off-by: default avatarPatrick Venture <venture@google.com>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent ece0c03a

drivers/hwmon/aspeed-pwm-tacho.c

+18 −6
Original line number Diff line number Diff line
@@ -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];