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From: Richard Weinberger <richard-/L3Ra7n9ekc@public.gmane.org>
To: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: Harald Geyer <harald-95f8Dae0BrPYtjvyW6yDsg@public.gmane.org>,
	"linux-gpio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-gpio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Javier Martinez Canillas
	<javier.martinez-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>,
	Alexandre Courbot
	<acourbot-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
	Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
	Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Hartmut Knaack <knaack.h-Mmb7MZpHnFY@public.gmane.org>,
	Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>,
	Peter Meerwald <pmeerw-jW+XmwGofnusTnJN9+BGXg@public.gmane.org>,
	"linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: iio: dht11 broken
Date: Mon, 01 Dec 2014 15:18:39 +0100	[thread overview]
Message-ID: <547C78BF.3030709@nod.at> (raw)
In-Reply-To: <CACRpkdbSUJMF_1_8aZ+ECHAT+ztsa4jXuSFo_+V9gr1MzsNCcg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

Am 01.12.2014 um 15:08 schrieb Linus Walleij:
> On Mon, Dec 1, 2014 at 11:59 AM, Richard Weinberger <richard-/L3Ra7n9ekc@public.gmane.org> wrote:
>> Am 01.12.2014 um 11:49 schrieb Harald Geyer:
> 
>>> Any input from gpiolib people about what the proper fix would be in
>>> their opinion, of course is appreciated. I don't think the dht11 driver
>>> is doing anything unreasonable per se, so maybe they can clarify how
>>> the API is intended to be used?
>>
>> Your driver sets up a GPIO as IRQ and then you switch the mode to output
>> to enable the DHT sensor.
>> This is not an API issue, it is an design issue.
>> I'm not a hardware expert but AFAIK setting an IRQ pin into output mode can
>> lead to undefined behavior.
> 
> Well that check is there exactly to prevent madness like this.
> 
> IRQs on pins set to output *does* *not* *make* *sense*.
> 
> Remove the IRQ before setting the pin to output and vice
> versa and everyone will be happier.

Thanks for the confirmation.
I'll cook up a patch.

Thanks,
//richard

WARNING: multiple messages have this Message-ID (diff)
From: Richard Weinberger <richard@nod.at>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Harald Geyer <harald@ccbib.org>,
	"linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>,
	Javier Martinez Canillas <javier.martinez@collabora.co.uk>,
	Alexandre Courbot <acourbot@nvidia.com>,
	Stephen Warren <swarren@nvidia.com>,
	Jonathan Cameron <jic23@kernel.org>,
	Hartmut Knaack <knaack.h@gmx.de>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Peter Meerwald <pmeerw@pmeerw.net>,
	"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: iio: dht11 broken
Date: Mon, 01 Dec 2014 15:18:39 +0100	[thread overview]
Message-ID: <547C78BF.3030709@nod.at> (raw)
In-Reply-To: <CACRpkdbSUJMF_1_8aZ+ECHAT+ztsa4jXuSFo_+V9gr1MzsNCcg@mail.gmail.com>

Am 01.12.2014 um 15:08 schrieb Linus Walleij:
> On Mon, Dec 1, 2014 at 11:59 AM, Richard Weinberger <richard@nod.at> wrote:
>> Am 01.12.2014 um 11:49 schrieb Harald Geyer:
> 
>>> Any input from gpiolib people about what the proper fix would be in
>>> their opinion, of course is appreciated. I don't think the dht11 driver
>>> is doing anything unreasonable per se, so maybe they can clarify how
>>> the API is intended to be used?
>>
>> Your driver sets up a GPIO as IRQ and then you switch the mode to output
>> to enable the DHT sensor.
>> This is not an API issue, it is an design issue.
>> I'm not a hardware expert but AFAIK setting an IRQ pin into output mode can
>> lead to undefined behavior.
> 
> Well that check is there exactly to prevent madness like this.
> 
> IRQs on pins set to output *does* *not* *make* *sense*.
> 
> Remove the IRQ before setting the pin to output and vice
> versa and everyone will be happier.

Thanks for the confirmation.
I'll cook up a patch.

Thanks,
//richard

  parent reply	other threads:[~2014-12-01 14:18 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-30 16:23 iio: dht11 broken Richard Weinberger
2014-12-01 10:49 ` Harald Geyer
2014-12-01 10:59   ` Richard Weinberger
     [not found]     ` <547C4A26.3070108-/L3Ra7n9ekc@public.gmane.org>
2014-12-01 14:08       ` Linus Walleij
2014-12-01 14:08         ` Linus Walleij
     [not found]         ` <CACRpkdbSUJMF_1_8aZ+ECHAT+ztsa4jXuSFo_+V9gr1MzsNCcg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-12-01 14:18           ` Richard Weinberger [this message]
2014-12-01 14:18             ` Richard Weinberger

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