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Linux/TPS659038-Q1: ADC start conversion failed

Part Number: TPS659038-Q1

Tool/software: Linux

Hi All,

We're using AM5728 for our product. 

Sometimes in the kernel logs through dmesg, we see below lines in the logs:

[ 8632.351524] palmas-gpadc 48070000.i2c:tps659038@58:gpadc: conversion not completed
[ 8632.361861] palmas-gpadc 48070000.i2c:tps659038@58:gpadc: ADC start conversion failed
[ 8637.378529] palmas-gpadc 48070000.i2c:tps659038@58:gpadc: conversion not completed
[ 8637.388763] palmas-gpadc 48070000.i2c:tps659038@58:gpadc: ADC start conversion failed
[ 8642.405528] palmas-gpadc 48070000.i2c:tps659038@58:gpadc: conversion not completed
[ 8642.413882] palmas-gpadc 48070000.i2c:tps659038@58:gpadc: ADC start conversion failed

We use palmas-gpadc for the tps659038 PMIC.

QUESTION:


I was curious what is the cause of this errors in the kernel logs?

Do they harm anyways?

What is the workaround to fix this issue?

Thanks,

Divyeshkumar

  • Hello Divyeshkumar,

    This error means that the GPADC conversion is never completing.

    The most likely cause is if you are using an automatic conversion, the GPADC can get locked up if an automatic conversion is interrupted by a cold reset or disabling the auto conversion. If the conversion is interrupted in this way, future GPADC conversions will not complete until the GPADC is recovered from this lock state. Section 3.2 of the below app note suggests a procedure to check for that case, and a procedure for recovery.



    The errors don't indicate any harm, it just means that the GPADC is not returning any values. If the ADC results are not used in your system, then you can ignore it. If they are used in your system, you will likely want to implement the recovery routine so that you can get future ADC results.

    Regards,
    Karl