diff options
| author | Vic Yang <victoryang@chromium.org> | 2013-06-19 10:46:43 +0800 |
|---|---|---|
| committer | ChromeBot <chrome-bot@google.com> | 2013-06-19 17:12:35 -0700 |
| commit | c5d978baacc44220445ad7b5641bbdb7b634cbfa (patch) | |
| tree | b4560349f0f2940d99305e0cf9ae5f347c586cd8 | |
| parent | 89ee180156889ce0fab13fb1a2905bd2270ab8a9 (diff) | |
| download | chrome-ec-c5d978baacc44220445ad7b5641bbdb7b634cbfa.tar.gz | |
spring: Hard-limit current draw from Toad
The Toad cable is browning out from time to time. Let's limit its
current in aggressive mode.
Also fix a bug in hard current limit calculation.
BUG=None
TEST=Plug-in Toad cable and see PWM duty cycle starts higher.
BRANCH=Spring
Change-Id: I06d64418989aa32a99545986fe841914f054acde
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/59161
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
| -rw-r--r-- | common/extpower_usb.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/common/extpower_usb.c b/common/extpower_usb.c index 97034b1eec..5be7d2efc9 100644 --- a/common/extpower_usb.c +++ b/common/extpower_usb.c @@ -278,8 +278,14 @@ static int apple_charger_current(void) static int hard_current_limit(int limit) { + /* + * In aggressive mode, the PWM duty cycle goes lower than the nominal + * cycle for PWM_CTRL_OC_MARGIN. Therefore, increase duty cycle by + * PWM_CTRL_OC_MARGIN avoids going over the hard limit. + * (Note that lower PWM cycle translates to higher current) + */ if (current_limit_mode == LIMIT_AGGRESSIVE) - return limit - PWM_CTRL_OC_MARGIN; + return MIN(limit + PWM_CTRL_OC_MARGIN, 100); else return limit; } @@ -524,6 +530,8 @@ static void usb_update_ilim(int dev_type) current_limit = hard_current_limit(I_LIMIT_1500MA); else if (dev_type & TSU6721_TYPE_JIG_UART_ON) current_limit = hard_current_limit(I_LIMIT_2000MA); + else if (dev_type & TOAD_DEVICE_TYPE) + current_limit = hard_current_limit(I_LIMIT_500MA); pwm_nominal_duty_cycle(current_limit); } else { |