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analogdevicesinc / libiio

A cross platform library for interfacing with local and remote Linux IIO devices
http://analogdevicesinc.github.io/libiio/
GNU Lesser General Public License v2.1
483 stars 311 forks source link

iio_device_create_buffer() is broken on local #1111

Closed catkira closed 7 months ago

catkira commented 8 months ago

commit aba77ca961414bde29c9856ae3f6797bc6eab9c0 causes iio_device_create_buffer() to return Device or resource busy (16) when I run it on local.

catkira commented 8 months ago

@pcercuei can you quick fix this an cherry-pick the fix into pcercuei/fix-mmap ? <3

pcercuei commented 8 months ago

It's not broken - it's just that you have IIOD running on your board, that already has the buffer's file descriptor opened. As you can read from the commit message, there is a valid reason for it.

There might be a better solution, but it's far from an easy fix, and I'm in vacation until the 8th ;)

catkira commented 8 months ago

hmmm ok, it would be good if both could work at the same time like before. I will kill iiod after reboot until a better solution is found.

catkira commented 8 months ago

I have only BR2_PACKAGE_LIBIIO_IIOD_USBD enabled, this causes iiod to be started by the S23udc init.d script

image

I can stop by running S23udc stop but after that I still get the same error when trying to create a buffer.

catkira commented 8 months ago

oh I found it, I need to kill avahi-daemon as well. This is super inconvenient.

rgetz commented 8 months ago

you shouldn't need to kill avahi...

when you do a S23udc stop, do you get any errors?

If you edit the script so it is : start-stop-daemon -K -p /var/run/iiod.pid (remove) the -q (quiet) and 2>/dev/null what output do you get?

Thanks

catkira commented 8 months ago

@rgetz yes, the avahi thing was a mistake on my side, I was confused because S23udc started iiod which was not obvious for me

catkira commented 8 months ago

It seems like with the new buffer logic it is not even possible to two different iio contexts open inside an application or on two different applications. That's quite a big limitation, I don't know exactly what made this change necessary, but the way it was before was much more convenient for my use cases.

catkira commented 8 months ago

everytime a context is created, it opens the buffer of every iio device that is available in that context and therefore blocks it for all other contexts that are opened after it. Thats super unintuitive and very limiting.

catkira commented 8 months ago

it was probably done for the new event feature, can't this be implemented without breaking multi context support?

catkira commented 7 months ago

fixed with commit e9436e