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2a783457a9
poppy uses an ISL charger, which, unlike bd9995* charger based
systems, cannot provide an interrupt when VBUS falls below/rises
above a certain threshold.
On poppy rev2 onwards, we have a precise VBUS detection pin coming
from BC1.2 detection chip (PI3USB9281C), we a threshold between
3.1-3.7 V (3.5V typical) so we can use that to
enable discharge, according to this logic:
- When VBUS voltage falls below ~3.5V, and we're not sourcing 5V
to the port, enable discharge.
- When VBUS voltage rises above ~3.5V, disable discharge.
- When we source 5V to the port, disable discharge.
BRANCH=none
BUG=b:37525769
TEST=Charge out to device (Galaxy S8), and verify that VBUS
drops to 0.8V much faster than without this patch.
TEST=pd 0 swap power: 28ms (vs 496ms)
TEST=pd 1 swap power: 24ms to 0.875v, 202ms to 0.8v (vs 410ms)
TEST=Disconnect cable (port 0): 65ms (vs 721ms)
TEST=Disconnect cable (port 1): 13ms (vs 515ms)
Change-Id: Ibf2dcf5de31514fa0ce0ebd0c6db53d421a586fe
Reviewed-on: https://chromium-review.googlesource.com/481562
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
For an overview of the Embedded Controller firmware, refer to http://www.chromium.org/chromium-os/2014-firmware-summit For instructions on building from source, refer to http://www.chromium.org/chromium-os/ec-development/getting-started-building-ec-images-quickly