gru: Add USB 2.0 PHY tuning for Kevin

Hardware / Coreboot - Julius Werner [chromium.org] - 19 September 2016 17:32 UTC

This patch sets some magic number in magic undocumented registers that are rumored to make USB 2.0 signal integrity better on Kevin. I don't see any difference (unfortunately it doesn't solve the problems with long cables on my board), but I guess it doesn't hurt either way.

BRANCH=None BUG=chrome-os-partner:56108,chrome-os-partner:54788 TEST=Booted Kevin with USB connected through Servo. Seems to have roughly the same failure rate as before.

Change-Id: If31fb49f1ed7218b50f24e251e54c9400db72720

1c8491c gru: Add USB 2.0 PHY tuning for Kevin
src/mainboard/google/gru/mainboard.c | 9 +++++++++
src/soc/rockchip/rk3399/include/soc/grf.h | 2 +-
2 files changed, 10 insertions(+), 1 deletion(-)

Upstream: review.coreboot.org

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