From 1c8491c3ab75cc54c5288552b3ffb8513a3488aa Mon Sep 17 00:00:00 2001 From: Julius Werner Date: Mon, 15 Aug 2016 17:58:05 -0700 Subject: gru: Add USB 2.0 PHY tuning for Kevin 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 Signed-off-by: Martin Roth Original-Commit-Id: 0c5c8f0f80ea1ebb042bcb91506a6100833e7e84 Original-Change-Id: Ifbd47bf6adb63a2ca5371c0b05c5ec27a0fe3195 Original-Signed-off-by: Julius Werner Original-Reviewed-on: https://chromium-review.googlesource.com/370900 Original-Reviewed-by: Guenter Roeck Original-Reviewed-by: David Schneider Reviewed-on: https://review.coreboot.org/16265 Tested-by: build bot (Jenkins) Reviewed-by: Patrick Georgi --- src/mainboard/google/gru/mainboard.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'src/mainboard/google') diff --git a/src/mainboard/google/gru/mainboard.c b/src/mainboard/google/gru/mainboard.c index 8a6cda203d..a2b74badf2 100644 --- a/src/mainboard/google/gru/mainboard.c +++ b/src/mainboard/google/gru/mainboard.c @@ -158,6 +158,15 @@ static void configure_display(void) static void setup_usb(void) { + /* A few magic PHY tuning values that improve eye diagram amplitude + * and make it extra sure we get reliable communication in firmware. */ + /* Set max ODT compensation voltage and current tuning reference. */ + write32(&rk3399_grf->usbphy0_ctrl[3], 0x0fff02e3); + write32(&rk3399_grf->usbphy1_ctrl[3], 0x0fff02e3); + /* Set max pre-emphasis level, only on Kevin PHY0. */ + if (IS_ENABLED(CONFIG_BOARD_GOOGLE_KEVIN)) + write32(&rk3399_grf->usbphy0_ctrl[12], 0xffff00a7); + setup_usb_otg0(); setup_usb_otg1(); } -- cgit v1.2.3