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From: Peter Rosin <peda@axentia.se>
To: Kent Gibson <warthog618@gmail.com>
Cc: "linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>
Subject: Re: [libgpiod] Request an output line, without modifying the value
Date: Mon, 26 Apr 2021 06:34:12 +0200	[thread overview]
Message-ID: <ba9021bc-6558-910b-47ce-c2effb821fee@axentia.se> (raw)
In-Reply-To: <20210424062132.GA14885@sol>

On 2021-04-24 08:21, Kent Gibson wrote:
> On Fri, Apr 23, 2021 at 05:32:15PM +0200, Peter Rosin wrote:
>> Hi!
>>
>> I'm wondering if there is a way to request an output line using
>> libgpiod without clobbering the previous value. I would like for
>> an application to take a peek at this previous value of an output
>> gpio and behave slightly different for 0/1.
>>
>> Cheers,
>> Peter
> 
> Assuming it is still an output then GPIOD_LINE_REQUEST_DIRECTION_AS_IS
> should do what you are after.
> But there is no guarantee that the line state is preserved across
> requests, so YMMV.

Excellent suggestion, I'll try that. And now I of course feel silly for
not seeing it myself, it's so obvious...

Thanks a bunch!

Cheers,
Peter

      reply	other threads:[~2021-04-26  4:34 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-23 15:32 Request an output line, without modifying the value Peter Rosin
2021-04-24  6:21 ` [libgpiod] " Kent Gibson
2021-04-26  4:34   ` Peter Rosin [this message]

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