From ece0c03a9e5f727435d19754411e59c3ae28cbb8 Mon Sep 17 00:00:00 2001 From: Patrick Venture Date: Sat, 24 Jun 2017 08:39:32 -0700 Subject: hwmon: (aspeed-pwm-tacho) reduce fan_tach period Reduce the fan_tach period such that the fan controller uses a shorter period to measure the rpm. The original period of 0x1000 was chosen as a conversative value from the reference implementation. Through experimentation on the quanta-q71l board, I was able to drive the number down which ultimately reduced the time the controller would use to determine the fan_tach. This value was recently tested and accepted downstream on the IBM Zaius board which uses the ast2500. Future work: It may be worthwhile as this is a tunable parameter to the system, to allow overriding it through the device tree. Testing: Tested on an ast2400 sitting on a quanta-q71l and ast2500 on power9. Signed-off-by: Patrick Venture Signed-off-by: Guenter Roeck --- drivers/hwmon/aspeed-pwm-tacho.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/hwmon') diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-tacho.c index 86e2ea8..b2ab561 100644 --- a/drivers/hwmon/aspeed-pwm-tacho.c +++ b/drivers/hwmon/aspeed-pwm-tacho.c @@ -160,7 +160,7 @@ * 11: reserved. */ #define M_TACH_MODE 0x02 /* 10b */ -#define M_TACH_UNIT 0x1000 +#define M_TACH_UNIT 0x00c0 #define INIT_FAN_CTRL 0xFF struct aspeed_pwm_tacho_data { -- cgit v1.1