Help required debugging digikam/libgphoto2

[Mark Ovens]

Back in January I posted about a problem using my Canon EOS 400D in
digikam 0.9.3:

> Running under KDE 3.5.8 on FreeBSD 6.3-STABLE
>
> When I connect my Canon EOS400D (PTP Mode) the OS reports it as:
>
> ugen0: Canon Inc. Canon Digital Camera, rev 2.00/0.02, addr 2
>
> In digikam I connect to the camera, the camera window opens, displays
> "Connecting to camera", 'BUSY' appears on the camera LCD screen
> and the read/write LED flashes. Digikam then displays
> "Listing Folders....".
>
> When digikam has finished, there are no thumbnails displayed
> but the following appears in the console:
>
> digikam: Failed to get folders list from camera!
> digikam: Libgphoto2 error: Unspecified error (-1)
>
> It was suggested that gphoto2 may be the cause (Canon
> stability problems in 2.4.0) so I downgraded gphoto2 to 2.2.1
> but the problem persisted.
>
> I then downgraded digikam back to 0.9.2 and it works correctly -
> even with gphoto2 2.4.0 - so it definitely seems to be a problem
> with digikam 0.9.3
>
> Also, running gphoto2 from the commandline -
>
> ``gphoto2 --auto-detect -L''
>
> - works correctly.

Despite libgphoto2 being now at 2.4.1 which supposedly fixed a problem
with Canon cameras (which affect Linux users as well) this problem still
persists.

The error above comes from the call to

gp_camera_folder_list_folders()

in digikam/utilities/cameragui/gpcamera.cpp : GPCamera::getSubFolders()

     errorCode = gp_camera_folder_list_folders(d->camera,
QFile::encodeName(folder), clist, m_status->context);
     if (errorCode != GP_OK)
     {
         DDebug() << "Failed to get folders list from camera!" << endl;
         printGphotoErrorDescription(errorCode);
         gp_list_unref(clist);
         delete m_status;
         m_status = 0;
         return false;
     }

All the evdience suggests - to me at least - is that the problem is with
the interface between digikam 0.9.3 and libgphoto2 (any version) however
it is beyond my abilities to debug this any further.

I would like to get this fixed because although it isn't a showstopper
as I can put the CF card from the camera in a card reader, Canon cameras
have a neat feature whereby they 'tag' pictures as downloaded so when I
connect the camera I can just do Select->New Items in digikam and it
will pick up all the photos since the last time I downloaded them

So, can anyone with knowledge of the workings of digikam and/or
libgphoto2 give me some guidance on how to track down the cause of the
problem.

I'm perfectly happy to devote time to this but need help.

TIA

Mark