From: Lars-Peter Clausen <lars@metafoo.de>
To: Ezequiel Garcia <ezequiel.garcia@imgtec.com>,
Hartmut Knaack <knaack.h@gmx.de>,
Andrew Bresticker <abrestic@chromium.org>,
James Hartley <james.hartley@imgtec.com>,
Jonathan Cameron <jic23@kernel.org>
Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
robh+dt@kernel.org, Pawel.Moll@arm.com, Mark.Rutland@arm.com,
ijc+devicetree@hellion.org.uk, galak@codeaurora.org,
Naidu.Tellapati@imgtec.com, Phani Movva <Phani.Movva@imgtec.com>
Subject: Re: [PATCH v3 1/3] iio: adc: Cosmic Circuits 10001 ADC driver
Date: Thu, 27 Nov 2014 16:16:58 +0100 [thread overview]
Message-ID: <5477406A.8020403@metafoo.de> (raw)
In-Reply-To: <54773E63.4020300@imgtec.com>
[...]
>>>
>>>>>>> +
>>>>>>> + adc_dev->reg = devm_regulator_get(&pdev->dev, "vref");
>>>>>>> + if (IS_ERR_OR_NULL(adc_dev->reg))
>>>>>>> + return -EINVAL;
>>>>>> if (IS_ERR(adc_dev->reg))
>>>>>> return PTR_ERR(adc_dev->reg);
>>>>>
>>>>> Are you sure? What if devm_regulator_get() returns NULL?
>>>>>
>>>> I had a look at it, but couldn't figure out a condition in which it would return NULL. But I'd be happy to be informed of anything different.
>>>
>>> If CONFIG_REGULATOR=n you get NULL there (although I added a select REGULATOR
>>> on the v4 I just posted).
>>>
>> Indeed, thanks. Now I'm thinking if it would make sense to handle this special case in a special way (as it would be caused by an invalid kernel config). Well, I guess, I leave it up to you.
>
> Well, adding the select REGULATOR that shouldn't happen, so let's better
> drop the NULL check entirely.
Doing a 'select REGULATOR' can (and probably will sooner or later) create
nasty dependency loops. User selectable config items should not be selected
by another config item. If the driver really has a hard dependency on the
regulator framework then 'depends on REGULATOR' is the right thing to do.
- Lars
WARNING: multiple messages have this Message-ID (diff)
From: Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>
To: Ezequiel Garcia
<ezequiel.garcia-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>,
Hartmut Knaack <knaack.h-Mmb7MZpHnFY@public.gmane.org>,
Andrew Bresticker
<abrestic-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
James Hartley
<james.hartley-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>,
Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
Pawel.Moll-5wv7dgnIgG8@public.gmane.org,
Mark.Rutland-5wv7dgnIgG8@public.gmane.org,
ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org,
galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org,
Naidu.Tellapati-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org,
Phani Movva <Phani.Movva-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH v3 1/3] iio: adc: Cosmic Circuits 10001 ADC driver
Date: Thu, 27 Nov 2014 16:16:58 +0100 [thread overview]
Message-ID: <5477406A.8020403@metafoo.de> (raw)
In-Reply-To: <54773E63.4020300-1AXoQHu6uovQT0dZR+AlfA@public.gmane.org>
[...]
>>>
>>>>>>> +
>>>>>>> + adc_dev->reg = devm_regulator_get(&pdev->dev, "vref");
>>>>>>> + if (IS_ERR_OR_NULL(adc_dev->reg))
>>>>>>> + return -EINVAL;
>>>>>> if (IS_ERR(adc_dev->reg))
>>>>>> return PTR_ERR(adc_dev->reg);
>>>>>
>>>>> Are you sure? What if devm_regulator_get() returns NULL?
>>>>>
>>>> I had a look at it, but couldn't figure out a condition in which it would return NULL. But I'd be happy to be informed of anything different.
>>>
>>> If CONFIG_REGULATOR=n you get NULL there (although I added a select REGULATOR
>>> on the v4 I just posted).
>>>
>> Indeed, thanks. Now I'm thinking if it would make sense to handle this special case in a special way (as it would be caused by an invalid kernel config). Well, I guess, I leave it up to you.
>
> Well, adding the select REGULATOR that shouldn't happen, so let's better
> drop the NULL check entirely.
Doing a 'select REGULATOR' can (and probably will sooner or later) create
nasty dependency loops. User selectable config items should not be selected
by another config item. If the driver really has a hard dependency on the
regulator framework then 'depends on REGULATOR' is the right thing to do.
- Lars
next prev parent reply other threads:[~2014-11-27 15:16 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-13 14:13 [PATCH v3 0/3] iio: Add Cosmic Circuits ADC support Ezequiel Garcia
2014-11-13 14:13 ` Ezequiel Garcia
2014-11-13 14:13 ` [PATCH v3 1/3] iio: adc: Cosmic Circuits 10001 ADC driver Ezequiel Garcia
2014-11-13 14:13 ` Ezequiel Garcia
2014-11-15 10:46 ` Jonathan Cameron
2014-11-15 10:46 ` Jonathan Cameron
2014-11-15 18:05 ` Ezequiel Garcia
2014-11-15 18:05 ` Ezequiel Garcia
2014-11-22 1:15 ` Hartmut Knaack
2014-11-22 1:15 ` Hartmut Knaack
2014-11-25 17:46 ` Ezequiel Garcia
2014-11-25 17:46 ` Ezequiel Garcia
2014-11-25 21:41 ` Hartmut Knaack
2014-11-25 21:41 ` Hartmut Knaack
2014-11-25 22:03 ` Ezequiel Garcia
2014-11-25 22:03 ` Ezequiel Garcia
2014-11-25 22:53 ` Hartmut Knaack
2014-11-25 22:53 ` Hartmut Knaack
2014-11-27 15:08 ` Ezequiel Garcia
2014-11-27 15:08 ` Ezequiel Garcia
2014-11-27 15:16 ` Lars-Peter Clausen [this message]
2014-11-27 15:16 ` Lars-Peter Clausen
2014-11-27 15:18 ` Ezequiel Garcia
2014-11-27 15:18 ` Ezequiel Garcia
2014-11-13 14:13 ` [PATCH v3 2/3] DT: iio: adc: Add CC_10001 binding documentation Ezequiel Garcia
2014-11-13 14:13 ` Ezequiel Garcia
2014-11-13 14:37 ` Rob Herring
2014-11-13 14:37 ` Rob Herring
2014-11-13 18:18 ` Ezequiel Garcia
2014-11-13 18:18 ` Ezequiel Garcia
2014-11-13 18:19 ` [PATCH v4 " Ezequiel Garcia
2014-11-13 18:19 ` Ezequiel Garcia
2014-11-13 14:14 ` [PATCH v3 3/3] DT: Add a vendor prefix for Cosmic Circuits Ezequiel Garcia
2014-11-13 14:14 ` Ezequiel Garcia
2014-11-13 14:34 ` Rob Herring
2014-11-13 14:34 ` Rob Herring
2014-11-13 14:14 ` [PATCH v3 0/3] iio: Add Cosmic Circuits ADC support Ezequiel Garcia
2014-11-13 14:14 ` Ezequiel Garcia
2014-11-13 19:10 ` Andrew Bresticker
2014-11-13 19:10 ` Andrew Bresticker
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