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authorShawn Nematbakhsh <shawnn@chromium.org>2017-09-25 10:47:57 -0700
committerchrome-bot <chrome-bot@chromium.org>2017-09-26 13:36:20 -0700
commit3fe117d346e2a23d316cbdf038f95ccb62ac4565 (patch)
tree22e31f4a292a6c1c1171465fb1d1f004fdaf60a7 /board
parentff148ae240ab2ec4971279be55282a288e5c8c6f (diff)
downloadchrome-ec-3fe117d346e2a23d316cbdf038f95ccb62ac4565.tar.gz
samus_pd: Adjust input current limit downward to prevent OC
Based on measurements, Samus can pull more current than desired, even taking into account the existing INPUT_CURRENT_LIMIT_OFFSET_MA adjustment. Decrease the programmed current limit by an additional factor, determined by taking the worst-case power measurements across 15 different Samus devices, to ensure that Samus never pulls more current than desired. BUG=chrome-os-partner:55297 BRANCH=samus TEST=Verify with debug prints that curr_lim_ma becomes 256 when negotiated current limit is 500mA and curr_lim_ma becomes 2556 when negotiated limit is 3000mA. Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org> Change-Id: I6912d987c5a519f55a831698873a69c4cac817b8 Reviewed-on: https://chromium-review.googlesource.com/684696 Commit-Ready: Shawn N <shawnn@chromium.org> Tested-by: Shawn N <shawnn@chromium.org> Reviewed-by: Shawn N <shawnn@chromium.org>
Diffstat (limited to 'board')
-rw-r--r--board/samus_pd/board.c7
1 files changed, 2 insertions, 5 deletions
diff --git a/board/samus_pd/board.c b/board/samus_pd/board.c
index f20afd7985..bad38ed435 100644
--- a/board/samus_pd/board.c
+++ b/board/samus_pd/board.c
@@ -30,9 +30,6 @@
#define CPRINTS(format, args...) cprints(CC_USBCHARGE, format, ## args)
-/* Amount to offset the input current limit when sending to EC */
-#define INPUT_CURRENT_LIMIT_OFFSET_MA 192
-
/*
* When battery is high, system may not be pulling full current. Also, when
* high AND input voltage is below boost bypass, then limit input current
@@ -484,8 +481,8 @@ static int board_update_charge_limit(int charge_ma)
pwm_set_duty(PWM_CH_ILIM, pwm_duty);
#endif
- pd_status.curr_lim_ma = MAX(0, charge_ma -
- INPUT_CURRENT_LIMIT_OFFSET_MA);
+ pd_status.curr_lim_ma = charge_ma >= 500 ?
+ (charge_ma - 500) * 92 / 100 + 256 : 0;
CPRINTS("New ilim %d", charge_ma);
return 1;