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f4602ec472
We don't want the PPC to connect the CC lines from the TCPC to the USB connector until the TCPC resistors are set in a valid state (SINK initially). If we connect the CC lines (happens in the ppc_init) before setting the resistor values, some TCPC will be toggling the CC line between Rp/Rd since it doesn't detect a cable yet. In the dead battery charging case, connecting the toggling CC lines to the charger can rail the CC lines to 3.3 V signaling to the charger to disconnect Vbus, thus browning out the board. BRANCH=none BUG=b:71865251 TEST=Grunt powers on via usbc p0 with and without USB hub. Change-Id: I8e78aa2af42075398fab89a2dccef5e7df27b260 Signed-off-by: Jett Rink <jettrink@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/882305 Reviewed-by: Aseda Aboagye <aaboagye@chromium.org> Reviewed-by: Edward Hill <ecgh@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