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authorPatrick Venture <venture@google.com>2017-06-24 08:39:32 -0700
committerGuenter Roeck <linux@roeck-us.net>2017-06-24 08:57:42 -0700
commitece0c03a9e5f727435d19754411e59c3ae28cbb8 (patch)
tree6418c244170741841c65ff1b9a61238e25054bb4 /drivers/hwmon
parent3a2b3d37e1eecb75d792db2588b9eb7a471632cd (diff)
downloadop-kernel-dev-ece0c03a9e5f727435d19754411e59c3ae28cbb8.zip
op-kernel-dev-ece0c03a9e5f727435d19754411e59c3ae28cbb8.tar.gz
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 <venture@google.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Diffstat (limited to 'drivers/hwmon')
-rw-r--r--drivers/hwmon/aspeed-pwm-tacho.c2
1 files changed, 1 insertions, 1 deletions
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 {
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