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 <martinroth@chromium.org>
Original-Commit-Id: 0c5c8f0f80ea1ebb042bcb91506a6100833e7e84
Original-Change-Id: Ifbd47bf6adb63a2ca5371c0b05c5ec27a0fe3195
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/370900
Original-Reviewed-by: Guenter Roeck <groeck@chromium.org>
Original-Reviewed-by: David Schneider <dnschneid@chromium.org>
Reviewed-on: https://review.coreboot.org/16265
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/src/mainboard/google/gru/mainboard.c b/src/mainboard/google/gru/mainboard.c
index 8a6cda2..a2b74ba 100644
--- a/src/mainboard/google/gru/mainboard.c
+++ b/src/mainboard/google/gru/mainboard.c
@@ -158,6 +158,15 @@
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();
}