From: Kent Gibson <warthog618@gmail.com>
To: Peter Rosin <peda@axentia.se>
Cc: "linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>
Subject: Re: [libgpiod] Request an output line, without modifying the value
Date: Sat, 24 Apr 2021 14:21:32 +0800 [thread overview]
Message-ID: <20210424062132.GA14885@sol> (raw)
In-Reply-To: <6e26b4e5-277b-459f-29e7-7eb7e949e6a5@axentia.se>
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.
Cheers,
Kent.
next prev parent reply other threads:[~2021-04-24 6:21 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 ` Kent Gibson [this message]
2021-04-26 4:34 ` [libgpiod] " Peter Rosin
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