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Deep Sleep states (DS3, DS5) are a special mode of the Intel PCH chipset that has very limited wake capabilities and breaks a number of common user expected behahviors. In particular, when in Deep S3 the USB ports are turned off and cannot continue to charge, wake the system, or maintain their internal state as they will lose 5V power. This is particularly painful with gnubby devices as they will need unlocked after every DS3 suspend/resume cycle. The only external signal that the PCH uses to determine whether or not to enter Deep Sx states is the ACPRESENT (aka ACOK) pin. Currently this pin is simply buffered from the charger and will be asserted whenever a charger is connected. This change extends the EC control over the pin to also assert ACPRESENT if either Type-C port is currently supplying VBUS. Now when a USB device is inserted the system will be enter S3 state, but not go into Deep S3 state. This allows the USB device to continue to charge, maintain it's internal state, and wake the system. BUG=b:64406191 BRANCH=eve TEST=verify GPIO_PCH_ACOK pin from the EC in different scenarios and test that system goes into S3 or DS3 state as expected: 1) no charger, no USB device: ACOK not asserted, DS3 enabled 2) charger but no USB device: ACOK asserted, DS3 disabled 3) no charger but USB device: ACOK asserted, DS3 disabled 4) charger and USB device: ACOK asserted, DS3 disabled Change-Id: I1cd132459194382e418970d29b1b195d8132cfad Signed-off-by: Duncan Laurie <dlaurie@google.com> Reviewed-on: https://chromium-review.googlesource.com/896164 Reviewed-by: Furquan Shaikh <furquan@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