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authorJulius Werner <jwerner@chromium.org>2016-11-21 20:14:18 -0800
committerMartin Roth <martinroth@google.com>2016-12-06 21:56:01 +0100
commitc49782cbe7a79cca03c3c20c647211367bb0a03e (patch)
tree5df1d303241780f36bbbd38600b465d86760719c /Documentation
parentea79d2b3a3ddcb7909ac2862ebfda19c6b8823ae (diff)
google/gru: Power-cycle USB ports in developer/recovery modes
Gru only uses USB 2.0 in firmware to avoid all the madness associated with Type-C port orientation and USB 3.0 tuning. We do this by isolating the SuperSpeed lines in the Type-C PHY so it looks like they aren't connected to the device. Unfortunately, some devices seem to already get "locked" into SuperSpeed mode as soon as they detect Rx terminations once, and can never snap out again on their own. Since the terminations are already connected during power-on reset we cannot disable them fast enough to prevent this, and the only solution we found to date is to power-cycle the whole USB port. Now, Gru's USB port power is controlled by the EC, and unfortunately we have no direct host command to control it. We do however have a command to force a certain USB PD "role", and forcing our host into "sink" mode makes it stop sourcing power to the port. So for lack of a saner solution we'll use this to work around our problem. BRANCH=gru BUG=chrome-os-partner:59346 TEST=Booted Kevin in recovery mode, confirmed that my "problem stick" gets detected immediately (whereas previously I had to unplug/replug it). Booted Kevin to OS in both developer and normal mode and confirmed that USB still seems to work. Change-Id: Ib3cceba9baa170b13f01bd5c01bd413be5b441ba Signed-off-by: Patrick Georgi <pgeorgi@chromium.org> Original-Commit-Id: cd695eda33299e50362f1096c46f2f5260c49036 Original-Change-Id: I2db3d6d3710d18a8b8030e94eb1ac2e931f22638 Original-Signed-off-by: Julius Werner <jwerner@chromium.org> Original-Reviewed-on: https://chromium-review.googlesource.com/413031 Reviewed-on: https://review.coreboot.org/17628 Tested-by: build bot (Jenkins) Reviewed-by: Martin Roth <martinroth@google.com>
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