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!DRAFT! This document describes how to test the I2C demux feature on the newly added I2C busses on various R-Car Gen2 based boards.


Kernel Version and Configuration

Support for this feature is expected to land upstream in v4.16. It is currently available in a topic branch:

git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git renesas/topic/ip-switch-rework-2017

The shmobile_defconfig is suitable for these tests.

Hardware Environment

Busses on the following boards can be tested:

Board/SoC HW I2C bus # Linux I2C bus devicename
Lager/r8a7790 (R-Car H2 SoC) I2C2, I2C3 i2c-12, i2c-13
Koelsch/r8a7791 (R-Car M2-W SoC) I2C2, I2C4 i2c-13, i2c-14
Porter/r8a7791 (R-Car M2-W SoC) I2C2 i2c-10
Gose/r8a7793 (R-Car M2-N SoC) I2C2, I2C4 i2c-11, i2c-12
Alt/r8a7794 (R-Car E2 SoC) I2C1 i2c-11
Silk/r8a7794 (R-Car E2 SoC) I2C1 i2c-10

No hardware modifications are needed.

Software Environment

A busybox with standard commands like cd, cat, echo is needed. Also, i2cdump and i2cdetect from the i2c-tools package should be available.