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nyan*: Set GEN2 I2C pads to open-drain mode

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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.

Change-Id: I1b97f0c9c7580d1e532c3bdf7ac8690241ee7ee3
Signed-off-by: Ken Chang <kenc@nvidia.com>
Reviewed-on: https://chromium-review.googlesource.com/200996
Reviewed-by: Julius Werner <jwerner@chromium.org>
This commit is contained in:
Ken Chang 2014-05-22 10:54:16 +08:00 • committed by chrome-internal-fetch
commit 2db39166ec
3 changed files with 12 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

6
src/mainboard/google/nyan/mainboard.c
View file

@ -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);

6
src/mainboard/google/nyan_big/mainboard.c
View file

@ -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);

6
src/mainboard/google/nyan_blaze/mainboard.c
View file

@ -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);