Re: iio: iio_channel_get: ntc_thermistor isn't working since patch for of_iio_channel_get_by_name()

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Hello Guenter,

thank you for your quick answer.

2014-08-21 15:25 GMT+02:00 Guenter Roeck <linux@xxxxxxxxxxxx>:
> On Thu, Aug 21, 2014 at 09:29:56AM +0200, Johannes Pointner wrote:
>> Hello,
>>
>> I found out that since this patch https://lkml.org/lkml/2014/6/11/201,
>> which fixes the return values in this function, the ntc_thermistor
>> driver isn't working anymore for me.
>> The problem is that before the driver asked for probe deferral because
>> the adc driver isn't loaded at this point and now the probe fails in
>> the function iio_channel_get_sys and returns -ENODEV.
>> My question is: Who is in this case responsible to request a deferral?
>> The driver or the subsystem?
>>
> Unless I am missing something, iio_get_channel() should request probe deferral.
> There is no other way for the driver to know that the adc driver is not loaded
> yet.

Yes, I missed that. In the function __of_iio_channel_get the subsystem
returns a -EPROBE_DEFER.

>
> The problem here may be that the devicetree entry for the ntc_thermistor driver
> may not be correct. The above referenced patch fixes a bug in that area, and
> devicetree data is now better validated.
>
But the problem is, that this statement:
if (np && !of_get_property(np, "io-channel-ranges", NULL))
            return NULL;
overrides the -EPROBE_DEFER. Before the fix there was a break
statement and the -EPROBE_DEFER was returned.

Do I have made a mistake in the devicetree if I put the ntc
declaration directly under the root node?

> Guenter

Thanks in advance!

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