I saw on an oscilloscope that, when calling e.g. i2cget on i2c-0, that the speed is 400kHz.
I need it at 100kHz.
Then I found this forum thread:
The last post says that you just need to do this to alter the speed at runtime for testing:
echo 10000 > /sys/bus/i2c/devices/i2c-<BUS>/bus_clk_rate
The file “bus_clk_rate” does not exist under any of the i2c devices, though.
Is the NVIDIA code base used for your L4T image older than what the forum poster refers to?
How else would I change the I²C speed?
EDIT: btw, i2cdetect, on i2c-0, lists one address as “UU”, which apparently means the system is using that. Is there something conncted already for which a driver is being used? On the ixora board, or the module?
EDIT #2: Apart from the nice run-time experimental “echo to file” method linked above, which does not work with the L4T image, it seems modifying the device tree is the only way?
So I decompiled, modified, recompiled the /boot/tegra124-jetson_tk1-pm375-000-c00-00.dtb, stored it in /boot/ under another file name, and added another LABEL to /boot/extlinux/jetson-tk1_extlinux.conf.emmc, to get a boot option to start using the modified dtb on demand.
I am not presented with a boot option on the serial console, though.
Any ideas why not?