Errant readings on LM81 with T2080 SoC

[Chris Packham]

On 8/03/21 5:59 pm, Guenter Roeck wrote:
> On 3/7/21 8:37 PM, Chris Packham wrote:
> [ ... ]
>>> That's from -ENXIO which is used in only one place in i2c-mpc.c. I'll
>>> enable some debug and see what we get.
>> For the errant readings there was nothing abnormal reported by the driver.
>>
>> For the "No such device or address" I saw "mpc-i2c ffe119000.i2c: No
>> RXAK" which matches up with the -ENXIO return.
>>
> Id suggest to check the time until not busy and stop in mpc_xfer().
> Those hot loops are unusual, and may well mess up the code especially
> if preempt is enabled.
Reworking those loops seems to have had a positive result. I'll do a bit 
more testing and hopefully get a patch out later today.
>   Also, are you using interrupts or polling in
> your system ? The interrupt handler looks a bit odd, with "Read again
> to allow register to stabilise".
>
> Do you have fsl,timeout set in the devicetree properties and, if so,
> have you played with it ?
>
> Other than that, the only other real idea I have would be to monitor
> the i2c bus.
>
> Guenter