Re: iio:adc:ad799x driver broken after commit "Write default config on probe and reset alert status on probe"

Re: iio:adc:ad799x driver broken after commit "Write default config on probe and reset alert status on probe"

[Lars-Peter Clausen]

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On 11/25/2014 09:12 AM, Mike Looijmans wrote:
> After this commit:
>
>      iio:adc:ad799x: Write default config on probe and reset alert status on
> probe
>
>      writing ALERT_EN and BUSY_ALERT to the chip config register clears
>      pending alerts, BUSY_ALERT is cleared when reading back the register
>
> The AD7999 on our board no longer functions, reading the in_voltage*_raw
> sysfiles always returns "255" after this.
>
> I reverted the commit, and that fixed the problem for me.

I suspect that there is something going wrong when reading back the config 
register, can you check the attached patch and see what the output is?

Thanks,
- Lars


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diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c
index e37412d..babbdde 100644
--- a/drivers/iio/adc/ad799x.c
+++ b/drivers/iio/adc/ad799x.c
@@ -816,6 +816,8 @@ static int ad799x_probe(struct i2c_client *client,
 	if (ret < 0)
 		goto error_disable_reg;
 	st->config = ret;
+	dev_info(&client->dev, "config: %x %x\n", st->config,
+		st->chip_config->default_config);
 
 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
 		&ad799x_trigger_handler, NULL);

Re: iio:adc:ad799x driver broken after commit "Write default config on probe and reset alert status on probe"

[Mike Looijmans]

On 11/25/2014 03:03 PM, Lars-Peter Clausen wrote:
> On 11/25/2014 09:12 AM, Mike Looijmans wrote:
>> After this commit:
>>
>>      iio:adc:ad799x: Write default config on probe and reset alert status on
>> probe
>>
>>      writing ALERT_EN and BUSY_ALERT to the chip config register clears
>>      pending alerts, BUSY_ALERT is cleared when reading back the register
>>
>> The AD7999 on our board no longer functions, reading the in_voltage*_raw
>> sysfiles always returns "255" after this.
>>
>> I reverted the commit, and that fixed the problem for me.
>
> I suspect that there is something going wrong when reading back the config
> register, can you check the attached patch and see what the output is?
>
> Thanks,
> - Lars
>

The attached patch delivered the following output (using the current head code):

ad799x 1-0029: config: b 0



Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


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Re: iio:adc:ad799x driver broken after commit "Write default config on probe and reset alert status on probe"

[Lars-Peter Clausen]

On 11/26/2014 10:47 AM, Mike Looijmans wrote:
> On 11/25/2014 03:03 PM, Lars-Peter Clausen wrote:
>> On 11/25/2014 09:12 AM, Mike Looijmans wrote:
>>> After this commit:
>>>
>>>      iio:adc:ad799x: Write default config on probe and reset alert status on
>>> probe
>>>
>>>      writing ALERT_EN and BUSY_ALERT to the chip config register clears
>>>      pending alerts, BUSY_ALERT is cleared when reading back the register
>>>
>>> The AD7999 on our board no longer functions, reading the in_voltage*_raw
>>> sysfiles always returns "255" after this.
>>>
>>> I reverted the commit, and that fixed the problem for me.
>>
>> I suspect that there is something going wrong when reading back the config
>> register, can you check the attached patch and see what the output is?
>>
>> Thanks,
>> - Lars
>>
>
> The attached patch delivered the following output (using the current head
> code):
>
> ad799x 1-0029: config: b 0
>

Yea, kind of what I expected based on your description. Looking at the 
datasheet it seems the ad7999 doesn't even support register read back which 
would explain the issue. I'll try to find a board and see if I can fix it.

- Lars