Re: [libgpiod] gpiod_line_get_value_bulk may be broken?

[andy pugh <bodgesoc@xxxxxxxxx>]

On Thu, 27 Jul 2023 at 21:54, Kent Gibson <warthog618@xxxxxxxxx> wrote:

> That is not how the line_bulk API is used.
> You don't request the lines separately and then add them to the bulk,
> you add them to the bulk then request them with
> gpiod_line_request_bulk_input(), or one of the other
> gpiod_line_request_bulk_XXX() functions.

I did try that way first, but it didn't seem to be working for me.
I am currently upgrading the system to Bookworm (gpiod v1.6) to try again.

> Btw, the primary use case for the bulk is for when you need to perform
> operations on a set of lines as simultaneously as possible.

I am trying to do things as quickly as possible on a predetermined set
of lines.
I am experimenting with gpiod as a replacement for an existing (and
no-longer-working) driver that is part of LinuxCNC.

I suspect that gpiod won't be fast enough, ideally I would like to be
able to write to 15 IO lines in 15µs. (because the code will run in a
realtime thread which can't overrun)
(There are other reasons that it might not work too, you can probably
think of more than I can)

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912