diff options
| author | Bill Richardson <wfrichar@chromium.org> | 2014-11-05 12:43:57 -0800 |
|---|---|---|
| committer | chrome-internal-fetch <chrome-internal-fetch@google.com> | 2014-11-06 02:28:22 +0000 |
| commit | 41cde665166da1aced2ece17f7b503c78cdb5c8f (patch) | |
| tree | 6e95a130dadbd38846ad8cf32124ccdbb49ff353 /common/fan.c | |
| parent | f0809a23997d66265e625d23ebef8dba1465732f (diff) | |
| download | chrome-ec-41cde665166da1aced2ece17f7b503c78cdb5c8f.tar.gz | |
Samus: Handle fan startup in the EC, not the fan controller
The fans on samus have a recommended minimum duty cycle of 20%
while running, but 30% in order to start. We've been using the
EC's built-in fan controller for the start requirement, but it
has a minimum fast-start duty cycle of 50%. It turns out that
that speed is noticeably noisy.
This change handles the startup with logic in the EC instead, so
that the fan only tries to spin at 30% initially (or if it drops
too much below the minimum turning speed).
BUG=chrome-os-partner:33429
BRANCH=ToT,samus
TEST=make buildall -j
Boot the system, let it idle with the browser windows closed, the
browse a bit, then idle. Listen for changes to the fans.
Before, I could hear the fans kick in and out as the AP load
changed. Now it's much quieter.
Change-Id: Id35215520c064eb6843686ec8bb5f3618dac6cf6
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/227658
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Diffstat (limited to 'common/fan.c')
| -rw-r--r-- | common/fan.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/common/fan.c b/common/fan.c index db0b9a0d86..b99b770580 100644 --- a/common/fan.c +++ b/common/fan.c @@ -15,6 +15,10 @@ #include "system.h" #include "util.h" +/* Console output macros */ +#define CPUTS(outstr) cputs(CC_THERMAL, outstr) +#define CPRINTS(format, args...) cprints(CC_THERMAL, format, ## args) + /* True if we're listening to the thermal control task. False if we're setting * things manually. */ static int thermal_control_enabled[CONFIG_FANS]; @@ -44,14 +48,29 @@ int fan_percent_to_rpm(int fan, int pct) /* The thermal task will only call this function with pct in [0,100]. */ test_mockable void fan_set_percent_needed(int fan, int pct) { - int rpm; + int actual_rpm, new_rpm; + static int prev_rpm[CONFIG_FANS]; if (!thermal_control_enabled[fan]) return; - rpm = fan_percent_to_rpm(fan, pct); + new_rpm = fan_percent_to_rpm(fan, pct); + actual_rpm = fan_get_rpm_actual(fans[fan].ch); - fan_set_rpm_target(fans[fan].ch, rpm); + /* If we want to turn and the fans are currently significantly below + * the minimum turning speed, we should turn at least as fast as the + * necessary start speed instead. */ + if (new_rpm && + actual_rpm < fans[fan].rpm_min * 9 / 10 && + new_rpm < fans[fan].rpm_start) + new_rpm = fans[fan].rpm_start; + + if (new_rpm != prev_rpm[fan]) { + CPRINTS("Fan %d %d%% => %d rpm", fan, pct, new_rpm); + prev_rpm[fan] = new_rpm; + } + + fan_set_rpm_target(fans[fan].ch, new_rpm); } static void set_enabled(int fan, int enable) |