Issue with i2c-bcm2835 module with I2C devices?

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
25/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
c

Research direction

Start by reproducing the PiJuice communication error on a Pi 4B with the default i2c-bcm2835 module, then compare it with dtoverlay=i2c-bcm2708 in /boot/config.txt and the i2cdetect results. Done means explaining the Pi 4B difference and identifying a concrete kernel fix or documented limitation; the report provides no source file or test to begin from.

Written by the indexing model from the issue text.

Description

When trying the PiJuice on Pi 4B using Raspbian Buster out of the box we get a COMMUNICATION ERROR in the PiJuice software although i2cdetect reported the usual addresses (0x14 and 0x68).

Turned out we had to use the older i2c-bcm2708 module instead of the default i2c-bcm2835 module.

With 'dtoverlay=i2c-bcm2708' in /boot/config.txt both the PiJuice HAT and Zero work.

On the Pi 3B+ the PiJuice works fine with the default i2c-bcm2835 module.

Do not know what the differences are in the new BCM2711 SoC w.r.t. I2C hardware.

Is there any known issues that might be causing this?

Dominant language
C
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