diff options
| author | Bill Richardson <wfrichar@chromium.org> | 2014-10-21 14:21:45 -0700 |
|---|---|---|
| committer | chrome-internal-fetch <chrome-internal-fetch@google.com> | 2014-10-22 02:23:39 +0000 |
| commit | 8cd9856cf8ef193ea094cf91c67e9aff25b2b521 (patch) | |
| tree | 966a17e7cb8edf8fd6ae8ad6b410fd4b124759e1 /chip/lm4/fan.c | |
| parent | 7eaa290c35a1ca5571854c7d31a5a125af665b65 (diff) | |
| download | chrome-ec-8cd9856cf8ef193ea094cf91c67e9aff25b2b521.tar.gz | |
samus: change fan RPM values, enable fast-start
Updating the fan speeds according to the manufacturer's specs.
The fan vendor recommends that the minimum fan speed be a 20%
duty cycle. Since the built-in fan controller has a tach-based
feedback loop, I'm using the RPM value instead of the duty cycle
(20% is 2286 RPM, according to the vendor).
The vendor also wants a 30% duty cycle to start turning, but the
built-in fan controller provides support for fast-start too. The
controller's minimum fast-start duty cycle is 50%, but it also
has a programmable number of revolutions that it will wait before
backing off.
Holding my ear down close to the fans while they start and stop,
it seems that the minimum 2 revolution start period is sufficient
and provides the least noise. Of course, since I've never had any
problems starting the fans directly at 1000 RPM this noise is a
little more noticeable than that. It's quite possible that the
built-in controller is smart enough to make 1000 RPM work by
bumping the duty cycle up until the fans turn even if the fans
don't like it.
BUG=chrome-os-partner:32892
BRANCH=ToT,samus
TEST=manual
Listen closely and run the EC console "faninfo" command to see
the fans start and stop as the system boots and idles.
Change-Id: I47c9e7cef3f9f4bd815a13032fe10234decd62ed
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/224830
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Diffstat (limited to 'chip/lm4/fan.c')
| -rw-r--r-- | chip/lm4/fan.c | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/chip/lm4/fan.c b/chip/lm4/fan.c index 8ec25bc1f8..1180d51906 100644 --- a/chip/lm4/fan.c +++ b/chip/lm4/fan.c @@ -132,7 +132,9 @@ int fan_is_stalled(int ch) void fan_channel_setup(int ch, unsigned int flags) { - if (flags & FAN_USE_RPM_MODE) { + uint32_t init; + + if (flags & FAN_USE_RPM_MODE) /* * Configure automatic/feedback mode: * 0x8000 = bit 15 = auto-restart @@ -146,8 +148,8 @@ void fan_channel_setup(int ch, unsigned int flags) * (see note at top of file) * 0x0000 = bit 0 = automatic control */ - LM4_FAN_FANCH(ch) = 0x802c; - } else { + init = 0x802c; + else /* * Configure drive-only mode: * 0x0000 = bit 15 = no auto-restart @@ -159,8 +161,17 @@ void fan_channel_setup(int ch, unsigned int flags) * 0x0000 = bits 3:2 = 1 pulses per revolution * 0x0001 = bit 0 = manual control */ - LM4_FAN_FANCH(ch) = 0x0001; - } + init = 0x0001; + + if (flags & FAN_USE_FAST_START) + /* + * Configure fast-start mode + * 0x0000 = bits 10:8 = start period (2<<0) edges + * 0x0040 = bits 7:6 = fast start at 50% duty + */ + init |= 0x0040; + + LM4_FAN_FANCH(ch) = init; } static void fan_init(void) |