I have an AML-S905X-CC running Raspbian that I would like to use to programmatically configure my monitor (specifically dim and brighten the backlight) but trying to use ddcutil with the i2c bus on the HDMI interface isn’t working. The monitor is a Dell P2421, DDC/CI is enabled in the OSD menu, and I confirmed being able to use DDC/CI to control the monitor using a different Windows machine. When I run ddcutil detect on the Potato I get the following:
Invalid display
I2C bus: /dev/i2c-0
DRM connector: card0-HDMI-A-1
EDID synopsis:
Mfg id: DEL - Dell Inc.
Model: DELL P2421
Product code: 41330 (0xa172)
Serial number: 3RYR613
Binary serial number: 809842764 (0x3045384c)
Manufacture year: 2022, Week: 8
DDC communication failed
i2cdetect -y 0 doesn’t show anything around 0x37 or 0x38 as I’d expect, result is below:
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: 30 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: 50 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
ddcutil environment doesn’t seem to show anything problematic either so I’m wondering if what I’m trying to do is even possible with the Potato?