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authorKen Chang <kenc@nvidia.com>2014-05-22 10:54:16 +0800
committerMarc Jones <marc.jones@se-eng.com>2014-12-31 05:26:51 +0100
commita859aa3df5c56f7d0d2d0969c4de601b93e4c101 (patch)
tree93e65df3be79ab72a814fdc6bf79faffaa1312ab /src/mainboard/google/nyan_big
parent9e208bc357b9357c05ad05fe4482ffaeb0047312 (diff)
downloadcoreboot-a859aa3df5c56f7d0d2d0969c4de601b93e4c101.tar.xz
nyan*: Set GEN2 I2C pads to open-drain mode
The VDDIO to GEN2 I2C SCL/SDA pins is 1.8V and the external pull-up voltage is 3.3V (the external 3.3V > I/O 1.8V) thus the pinmux E_OD bit of these two pins needs to be set to ensure GEN2 I2C pads work fine on 3.3V. BRANCH=nyan BUG=none TEST=observed voltage drop from 3.3V to 2.36V on gen2 i2c on blaze w/o this change. the waveform looks good on both scl/sda pins w/ this change. Original-Change-Id: I1b97f0c9c7580d1e532c3bdf7ac8690241ee7ee3 Original-Signed-off-by: Ken Chang <kenc@nvidia.com> Original-Reviewed-on: https://chromium-review.googlesource.com/200996 Original-Reviewed-by: Julius Werner <jwerner@chromium.org> (cherry picked from commit 2db39166ec525e56a19746f38a867305a2687365) Signed-off-by: Marc Jones <marc.jones@se-eng.com> Change-Id: I0c84eade89311baf0a6f180cb5cc9e2145f6b7ea Reviewed-on: http://review.coreboot.org/7952 Tested-by: build bot (Jenkins) Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Diffstat (limited to 'src/mainboard/google/nyan_big')
-rw-r--r--src/mainboard/google/nyan_big/mainboard.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/src/mainboard/google/nyan_big/mainboard.c b/src/mainboard/google/nyan_big/mainboard.c
index 4a55e1e3a2..ff147e2c15 100644
--- a/src/mainboard/google/nyan_big/mainboard.c
+++ b/src/mainboard/google/nyan_big/mainboard.c
@@ -81,10 +81,12 @@ static void setup_pinmux(void)
PINMUX_GEN1_I2C_SDA_FUNC_I2C1 | PINMUX_INPUT_ENABLE);
// I2C2 clock.
pinmux_set_config(PINMUX_GEN2_I2C_SCL_INDEX,
- PINMUX_GEN2_I2C_SCL_FUNC_I2C2 | PINMUX_INPUT_ENABLE);
+ PINMUX_GEN2_I2C_SCL_FUNC_I2C2 | PINMUX_INPUT_ENABLE |
+ PINMUX_OPEN_DRAIN);
// I2C2 data.
pinmux_set_config(PINMUX_GEN2_I2C_SDA_INDEX,
- PINMUX_GEN2_I2C_SDA_FUNC_I2C2 | PINMUX_INPUT_ENABLE);
+ PINMUX_GEN2_I2C_SDA_FUNC_I2C2 | PINMUX_INPUT_ENABLE |
+ PINMUX_OPEN_DRAIN);
// I2C4 (DDC) clock.
pinmux_set_config(PINMUX_DDC_SCL_INDEX,
PINMUX_DDC_SCL_FUNC_I2C4 | PINMUX_INPUT_ENABLE);