linux-kernel - Re: [PATCH] iio: adc: Nothing in ADC should be a bool CONFIG

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Date:	Thu, 24 Apr 2014 13:23:06 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Jonathan Cameron <jic23@...nel.org>,
	Naveen Krishna Chatradhi <ch.naveen@...sung.com>
Cc:	Lars-Peter Clausen <lars@...afoo.de>, Milo.Kim@...com,
	Lee Jones <lee.jones@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Russ.Dill@...com, alexandre.belloni@...e-electrons.com,
	oleksandr.kozaruk@...com, B38611@...escale.com,
	johannes.thumshirn@....de, sre@...ian.org,
	Sachin Kamat <sachin.kamat@...aro.org>,
	linux-iio <linux-iio@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: adc: Nothing in ADC should be a bool CONFIG

Jonathan / Naveen,

On Wed, Apr 23, 2014 at 9:37 PM, Jonathan Cameron <jic23@...nel.org> wrote:
> On 23/04/14 22:54, Doug Anderson wrote:
>>
>> Jonathan,
>>
>> On Wed, Apr 23, 2014 at 1:54 PM, Jonathan Cameron <jic23@...nel.org>
>> wrote:
>>>
>>> On 22/04/14 01:03, Doug Anderson wrote:
>>>>
>>>>
>>>> The whole IIO subsystem can be moved to a module.  If you make it a
>>>> module then stuff marked as "Y" in the adc directory simply won't be
>>>> linked in properly.
>>>>
>>>> The two configs that were wrong were EXYNOS_ADC and LP8788_ADC.  I
>>>> know for a fact that EXYNOS_ADC will work as a module (though it
>>>> appears to crash when you unload it--that needs to be addressed
>>>> separately).
>>>
>>>
>>> I'd really like to see this pinned down before taking this patch.
>>> I can see you argument that the current approach is clearly wrong,
>>> but swapping one issue for another is not an approach I'd particularly
>>> like to take...
>>>
>>> I can't immediately spot the cause of the crash, but there are certainly
>>> some interesting order issues in this driver.  Not enabling the vdd
>>> regulator until after the userspace interfaces are exposed (by the
>>> iio_device_register call) is interesting for a start.
>>>
>>> The remove doesn't run in the reverse of the probe order (see clocks
>>> vs regulators for example.)
>>>
>>> Gah, my reviewing for one clearly missed some things in this driver.
>>
>>
>> OK, fair enough.  I took a quick look and couldn't spot anything
>> either.  I've requested that Samsung dig into these problems.  If they
>> are unable to I will take a crack at it as time permits.  ;)
>>
> Cool and good luck (either way ;)

Ah ha!  Naveen pointed out that it was the "device_for_each_child"
that was the source of the crash.  ...and here's the problem...  I
think this is what we want:

-       ret = of_platform_populate(np, exynos_adc_match, NULL, &pdev->dev);
+       ret = of_platform_populate(np, exynos_adc_match, NULL, &indio_dev->dev);

-       device_for_each_child(&pdev->dev, NULL,
+       device_for_each_child(&indio_dev->dev, NULL,

Naveen has been volunteered to send the patch up.  ;)  Naveen:
hopefully you can address Jonathan's other concerns as well.  ;)

-Doug
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