Re: [libgpiod] bug: pull-up does not work

[Kent Gibson <warthog618@gmail.com>]

On Fri, Mar 25, 2022 at 11:02:07AM +0100, Jiří Prchal wrote:
> Hi,
> since in debian is 1.6.2 and pull-up doesn't work so I cloned git, branch
> next/libgpiod-2.0 and compiled libgpiod and tools, but no luck, same result.
> 

You mean it doesn't work for you on your platform.

The libgpiod-2.0 branch is a work in progress and should not be considered
the place to go to find solutions to problems with v1.6.
Not that I'm saying that the v2 branch doesn't work, I'm actually pretty
sure it does, but its purpose is to switch to the latest kernel uAPI, not
to provide fixes, should they be needed, for v1.6.

> ~# uname -r
> 5.17.0-rc7_cpm9g25
> 
> floating pins should go with pull-up/down
> ~# gpioget -B pull-up 3 6 8 10 12 14 16 18 20
> 0 0 0 0 0 0 0 0
> ~# gpioget -B pull-up 3 6 8 10 12 14 16 18 20
> 1 1 0 0 0 0 0 0
> ~# gpioget -B pull-up 3 6 8 10 12 14 16 18 20
> 0 1 0 1 0 0 0 0
> 
> ~# gpioget -v
> gpioget (libgpiod) v2.0-devel
> 
> Whats wrong with it?

You forgot to mention which of those pins are floating.
Or what gpiochip3 is and whether it supports biasing.

So does your chip support pull-up/down?
The kernel can only enable it if the hardware and pinctrl driver supports it.
If the hardware doesn't support it then attempting to set the
pull-up/down is quietly ignored, which would be consistent with what you
are seeing.

Cheers,
Kent.