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Date:      Tue, 24 Nov 2020 17:45:44 -0300
From:      "Dr. Rolf Jansen" <freebsd-rj@obsigna.com>
To:        Ian Lepore <ian@freebsd.org>
Cc:        freebsd-arm@freebsd.org
Subject:   Re: User Space GPIO Interrupt programming - GSoC-2018
Message-ID:  <2126F3C0-D877-4483-9041-9FC84B9C8D3E@obsigna.com>
In-Reply-To: <b4deea7dbe1f6890bf81357b3afd74561588bb76.camel@freebsd.org>
References:  <2B01780F-D367-48A3-A827-B479030A496D@obsigna.com> <b4deea7dbe1f6890bf81357b3afd74561588bb76.camel@freebsd.org>

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> Am 24.11.2020 um 17:32 schrieb Ian Lepore <ian@freebsd.org>:
>=20
> On Tue, 2020-11-24 at 17:14 -0300, Dr. Rolf Jansen wrote:
>> Hello
>>=20
>> Has anything of the GSoC-2018 efforts made it into the current code
>> base?
>>=20
>>=20
> =
https://wiki.freebsd.org/SummerOfCode2018Projects/UserSpaceGPIOinterrupts
>>=20
>> I installed the recent 13.0-CURRENT snapshot (2020-11-19) on a
>> BeagleBone Black which was one of the implementation targets of said
>> project, but when running the test tools, I either see cannot
>> read/kevent/poll/aio_read - Operation not supported by device or
>> Inappropriate ioctl for device.
>>=20
>> Perhaps I need to pull the project=E2=80=99s changes into the kernel =
by
>> myself. However, before this I would like to ask whether it is worth
>> the effort.
>>=20
>> Please, can anyone shed some light on this.
>>=20
>> Best regards
>>=20
>> Rolf
>>=20
>=20
> I have had that webpage open (but docked) for literally a year,
> eternally hoping that I can find time to get to it and somehow get it
> committed, or maybe use it as the basis for something to be committed
> (I haven't even looked at it close enough to see if it's =
commit-quality=20
> code or what).
>=20
> I'm curious: What particular need do you have for userspace gpio
> interrupts?  What would you like the API to look like (do you like the
> things listed at that page, or would you prefer something else)?
>=20
> Interrupts is probably not a good name, because it isn't really going
> to act like an interrupt does for kernel code.  It's really just pin-
> change notifications delivered to userland.

I was asked to jump into a project where push buttons and pulses from a =
rotary encoder (all connected to GPIO's) would invoke some programmed =
actions. Polling the GPIO's would be too faulty. To me "pin-change =
notifications delivered to userland" sounds not too bad for my purpose. =
However, I won't say no for a real threaded GPIO interrupt handler =
facility, which presumably would serve perfectly as well.

Thank you for answering

Best regards

Rolf=



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