Change in coreboot[master]: mb/google/dedede/var/blipper: Configure I2C times for touchpad/touchp...

[zanxi chen (Code Review)]

Attention is currently required from: Furquan Shaikh, zanxi chen, Henry Sun, Paul Menzel, Tao Xia, Karthikeyan Ramasubramanian.
zanxi chen has uploaded a new patch set (#5) to the change originally created by Tao Xia. ( https://review.coreboot.org/c/coreboot/+/54249 )

Change subject: mb/google/dedede/var/blipper: Configure I2C times for touchpad/touchpanel/codec
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mb/google/dedede/var/blipper: Configure I2C times for touchpad/touchpanel/codec

Configure I2C rise/fall time in device tree to ensure I2C
CLK runs accurately at I2C_SPEED_FAST (<400 kHz).

Measured I2C frequency changes are just as below after tuning:
touchpad: 434kHz ---> 391kHz
touchpanel: 439kHz ---> 382kHz
audio codec RT5682: 445kHz ---> 385kHz

BUG=b:187555396
BRANCH=dedede
TEST=Build and check after tuning I2C clock is under 400 kHz

Signed-off-by: Tao Xia 
Change-Id: I8438e37be49f8a74f53fd8460110dac1a3f06993
---
M src/mainboard/google/dedede/variants/blipper/overridetree.cb
1 file changed, 6 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/49/54249/5