AW: complete-request callback not called in Qt5 program

[Barnabás Pőcze]

Forwarding this to the mailing list.

2025. 05. 15. 16:08 keltezéssel, Stefan Geißler írta:
> Hi
> 
> I found the error. I used the wrong MIPI port, on which no camera was connected to.
> After correcting that, the program works nicely.
> 
> Case can be closed.
> 
> Best regards
> Stefan
> 
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: Barnabás Pőcze <barnabas.pocze at ideasonboard.com>
> Gesendet: Thursday, 15 May 2025 15:29
> An: Stefan Geißler <stefan.geissler at theimagingsource.com>
> Cc: libcamera-devel at lists.libcamera.org
> Betreff: Re: complete-request callback not called in Qt5 program
> 
> Hi
> 
> 2025. 05. 15. 12:12 keltezéssel, Stefan Geißler írta:
>> Hello
>>
>> I use libcamera 0.5 in C++ in a Qt5 program on an NXP 8.
>>
>> The callback for the request completed is not called, while the program runs.
> 
> How do you confirm that? The steps I would take:
> 
>     1. attach a debugger and place a breakpoint to confirm that it is not called
>     2. use `strace` to check if there are any `ioctl(VIDIOC_DQBUF, ...)`
>     3. attach a debugger and inspect the stack traces of all threads
>        to see if anything in libcamera or your code is maybe waiting for
>        a futex or similar
> 
> 
>>
>> It is called after I ended the program.
> 
> Can you clarify what you mean by this? When a camera is stopped, all outstanding requests should be returned to the application as "cancelled". Maybe that is what you're seeing.
> 
> 
>>
>> The libcamera source code is based on the C++ code in the tutorial.
>>
>> The C++ tutorial code as command line program works well.
> 
> In that case you should check if the camera is properly configured and started, and if enough requests are actually queued. You could run both with `LIBCAMERA_LOG_LEVELS=DEBUG` and potentially compare them.
> 
> 
> Regards,
> Barnabás Pőcze
> 
>>
>> What am I missing?
>>
>> Thank you
>>
>> Stefan
>>
>