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| author | Randall Spangler <rspangler@chromium.org> | 2012-01-27 16:06:15 -0800 |
|---|---|---|
| committer | Randall Spangler <rspangler@chromium.org> | 2012-01-27 16:06:15 -0800 |
| commit | 861db4c6f341503fbd3573746b7b38adc3a4f89b (patch) | |
| tree | bffc6dcd8cc9f7e18d730beb7fba5bcff66f61d0 /chip/lm4/pwm.c | |
| parent | 05bc7eca930c01f582426654d143303fea724a02 (diff) | |
| download | chrome-ec-861db4c6f341503fbd3573746b7b38adc3a4f89b.tar.gz | |
Add workaround for fan controller to handle speeds more than 7000 rpm
Signed-off-by: Randall Spangler <rspangler@chromium.org>
BUG=chrome-os-partner:7718
TEST=manual
// enable fan
gpioset enable_vs 1
// set fan speed to 7000
fanset 7000
faninfo
// should report duty cycle about 65%, fan speed about 7000 rpm, status = 2
fanset 4000
faninfo
// should report duty cycle about 25%, fan speed about 4000 rpm, status = 2
fanset -1
// should report duty cycle 100%, fan speed about 8800 rpm, status = 3
Change-Id: Ib7d7df14ad240811e6e79bc1fc4ecf0e6841c334
Diffstat (limited to 'chip/lm4/pwm.c')
| -rw-r--r-- | chip/lm4/pwm.c | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/chip/lm4/pwm.c b/chip/lm4/pwm.c index a1810ab128..d877e721ab 100644 --- a/chip/lm4/pwm.c +++ b/chip/lm4/pwm.c @@ -1,4 +1,4 @@ -/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved. +/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved. * Use of this source code is governed by a BSD-style license that can be * found in the LICENSE file. */ @@ -17,6 +17,13 @@ #define MAX_RPM 0x1fff /* Max PWM for fan controller */ #define MAX_PWM 0x1ff +/* Scaling factor for requested/actual RPM for CPU fan. We need this because + * the fan controller on Blizzard filters tach pulses that are less than 64 + * 15625Hz ticks apart, which works out to ~7000rpm on an unscaled fan. By + * telling the controller we actually have twice as many edges per revolution, + * the controller can handle fans that actually go twice as fast. See + * crosbug.com/p/7718. */ +#define CPU_FAN_SCALE 2 /* Configures the GPIOs for the fan module. */ @@ -38,12 +45,16 @@ static void configure_gpios(void) int pwm_get_fan_rpm(void) { - return LM4_FAN_FANCST(FAN_CH_CPU) & MAX_RPM; + return (LM4_FAN_FANCST(FAN_CH_CPU) & MAX_RPM) * CPU_FAN_SCALE; } int pwm_set_fan_target_rpm(int rpm) { + /* Apply fan scaling */ + if (rpm > 0) + rpm /= CPU_FAN_SCALE; + /* Treat out-of-range requests as requests for maximum fan speed */ if (rpm < 0 || rpm > MAX_RPM) rpm = MAX_RPM; @@ -67,7 +78,7 @@ static int command_fan_info(int argc, char **argv) { uart_printf("Fan actual speed: %4d rpm\n", pwm_get_fan_rpm()); uart_printf(" target speed: %4d rpm\n", - LM4_FAN_FANCMD(FAN_CH_CPU) & MAX_RPM); + (LM4_FAN_FANCMD(FAN_CH_CPU) & MAX_RPM) * CPU_FAN_SCALE); uart_printf(" duty cycle: %d%%\n", ((LM4_FAN_FANCMD(FAN_CH_CPU) >> 16)) * 100 / MAX_PWM); uart_printf(" status: %d\n", @@ -203,9 +214,10 @@ int pwm_init(void) * 0x0000 = bits 10:8 = start period (2<<0) edges * 0x0000 = bits 7:6 = no fast start * 0x0020 = bits 5:4 = average 4 edges when calculating RPM - * 0x0008 = bits 3:2 = 4 pulses per revolution + * 0x000c = bits 3:2 = 8 pulses per revolution + * (see note at top of file) * 0x0000 = bit 0 = automatic control */ - LM4_FAN_FANCH(FAN_CH_CPU) = 0x8028; + LM4_FAN_FANCH(FAN_CH_CPU) = 0x802c; /* Configure keyboard backlight: * 0x0000 = bit 15 = auto-restart |