[alsa-devel] ASoC: cs4271: init/timing problem

[Pascal Huerst]

Hey Brian,

On 31.03.2015 23:01, Brian Austin wrote:
> On Tue, 31 Mar 2015, Pascal Huerst wrote:
> 
>> Hey all,
>>
>> We have a custom built hw, based on am335x and from time to time we need
>> to rmmod/modprobe the ASoC machine driver. Depending on the hw, the
>> first call to regmap_update_bits(..) in cs4271_codec_probe(..) fails
>> with -EREMOTEIO.
>>
>> The error is originated in:
>>
>> drivers/i2c/busses/i2c-omap.c
>>
>> and happens if no i2c package acknowledge is received by the host.
>>
>> I think this is a timing issue and on some devices, the codec is just
>> not ready yet, for communication.
>>
>> What is the right way to fix that? My attempt would be something like this:
> 
> The error you are referring to is a NACK from a device (CODEC). That is 
> usually seen when you dont have it hooked up correctly. Could also be that 
> the I2C bus is too fast. How fast are you running the bus?

clock-frequency is set to 100000, hence 100 kHz, which should be ok,
according to the datasheet.