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mb/siemens/mc_ehl2: Add dummy I2C devices to limit the I2C speed in OS 

In Linux, the I2C speed defaults to 400 kHz if there is no device
registered in ACPI which requests a different speed. Due to board
limitations (layout, bus load), 400 kHz are too fast which results in a
timing violation. Therefore, add a dummy I2C device to both used I2C
buses (I2C1 and I2C2) with a speed of 100 kHz. This will limit the bus
speed in Linux accordingly.

Change-Id: I507c53c9ec7f763cef18903609231b1a66ed98fa
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69306
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
This commit is contained in:
Werner Zeh 2022-11-07 15:15:58 +01:00 committed by Felix Held
parent 14612f698c
commit eda13db4e9
1 changed files with 14 additions and 1 deletions
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15
src/mainboard/siemens/mc_ehl/variants/mc_ehl2/devicetree.cb
View File

@ -144,8 +144,21 @@ chip soc/intel/elkhartlake
register "cap_charge" = "CHARGE_OFF"
device i2c 0x52 on end # RTC RV3028-C7
end
# Add dummy I2C device to limit BUS speed to 100 kHz in OS
chip drivers/i2c/generic
register "hid" = ""PRP0001""
register "speed" = "I2C_SPEED_STANDARD"
device i2c 0x7f on end
end
end
device pci 15.2 on # I2C2
# Add dummy I2C device to limit BUS speed to 100 kHz in OS
chip drivers/i2c/generic
register "hid" = ""PRP0001""
register "speed" = "I2C_SPEED_STANDARD"
device i2c 0x7f on end
end
end
device pci 15.2 on end # I2C2
device pci 15.3 on end # I2C3
device pci 16.0 hidden end # Management Engine Interface 1