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Fix Pullup/Pulldown setting in LibgpiodV2#2476

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pgrawehr merged 18 commits into
dotnet:mainfrom
pgrawehr:GpioFixing1
Feb 28, 2026
Merged

Fix Pullup/Pulldown setting in LibgpiodV2#2476
pgrawehr merged 18 commits into
dotnet:mainfrom
pgrawehr:GpioFixing1

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@pgrawehr

@pgrawehr pgrawehr commented Feb 22, 2026 •
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Fixes #2475, #2461

The "bias" mode setting on the LibgpiodV2 driver wasn't working correctly. There where two main issues:

  • When setting the mode to PullUp or PullDown, the pin needs to be (also) set to input.
  • When changing the mode (while the pin was kept open) the change was not applied because there was an early abort when the mode was already set to input.
Microsoft Reviewers: Open in CodeFlow

@pgrawehr
Remove Tests that don't work
7bc93fe 
Not sure how this ever worked - mocking Span<T> is not allowed
@pgrawehr
Stabilize test
2930178
@pgrawehr
This one is flaky, too
b9ead8b
@pgrawehr
Add missing pullup/pulldown test to LibGpiodV2Driver
2bfe136
@pgrawehr
Fix a typo
287fab8
@pgrawehr
This is indeed failing
a29c4a8
@pgrawehr
Assume setting the bias requires setting the direction, too
7b8dedd
@pgrawehr
No error, but doesn't do the trick?
9f920b6
@pgrawehr
It appears that it takes a moment for the value to become low/high
306ddb3
@pgrawehr
There's no longer an error, but the result appears undefined
a8cc99d
@pgrawehr
Try to find out where the error is
278c2e0
@pgrawehr
Maybe just the switching fails
a0fded1
@pgrawehr
Why does it work only the first time?
d4f48e3
@pgrawehr
Always configure the lines
c338ae2 
We would need to test both direction and bias, but that's
not worth it, since SetPinMode is not expected to be time
critical.
@pgrawehr
Still does not work
2e0a3b8
@pgrawehr
Cleanup test code
24bd301
@pgrawehr
More cleanup
e73af0a
@pgrawehr
Fix test
342d7e5
@dotnet-policy-service dotnet-policy-service Bot added the area-System.Device.Gpio Contains types for using general-purpose I/O (GPIO) pins label Feb 22, 2026
Ellerbach
Ellerbach approved these changes Feb 23, 2026
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Looks good and I know you've been testing all this on real hardware.

@raffaeler

raffaeler commented Feb 23, 2026

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Let's talk about it, my Pi5 is complaining with libgpiod2 detection used in all the tests

@pgrawehr

pgrawehr commented Feb 28, 2026

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Confirmed that it works on the RPI5 as well. I will separately investigate whether the the automatic detection works correctly.

@pgrawehr pgrawehr merged commit 90d8965 into dotnet:main Feb 28, 2026
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@pgrawehr pgrawehr mentioned this pull request Feb 28, 2026
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@raffaeler

raffaeler commented Feb 28, 2026

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Yes, I confirm the tests are running with the code of this PR.
I used the 64 bit version of Raspbian Trixie on RPi5.

@raffaeler raffaeler mentioned this pull request Mar 2, 2026
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area-System.Device.Gpio Contains types for using general-purpose I/O (GPIO) pins

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Libgpiod3 support

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@pgrawehr @raffaeler @Ellerbach