I upgraded to a Pentax K-S2.
Previously, Digikam used to be able to display the RAW images, and Batch Convert the RAWs to JPG. (even though the K-S2 was not officially supported)
After a series of package upgrades, it can still display the K-S2 RAW files, but can no longer Batch Convert them. I get, "failed to process item."
The K-S2 is on the list for UFRAW to handle in the future, but it still can't do it yet. I am patient.
I checked the list for Gphoto2 and the K-S2 isn't on there - however the instructions for reporting to gphoto2 appear to be for recognising the K-S2 as a camera, rather than being able to decode the RAW file; so it looks like my filing a report to gphoto2 is not going to be useful.
Actually, Gphoto2 wasn't installed, so I installed it on my system and Digikam still fails to process (in fact, given the above, I can't figure why it was able to process the K-S2 images in the first place! But, hey :-) )
So I have a RAW image for you here - http://www.msknight.com/IMGP2257.PEF
...and hope that it can be added properly soon.
I am aware that Mint is quite behind on many of the packages.

Reproducible: Always

Steps to Reproduce:
1. Add the PEF image to the batch queue
2. Put the convert to Jpeg tool in the queue
3. Process the queue

Actual Results:  
Batch conversion fails with "Failed to process item" error message

Expected Results:  
Expected to get a processed JPEG

Not sure how to classify this. It used to work despite the K-S2 not being formally supported, so I'm not sure whether to report this as a feature request, or a bug!
It is a major bug for me, as I am now without processing on either Digikam or UFRaw, so I have no tool to process my RAW images ... and presumably this will hit anyone else with a K-S2.
Thank you for your efforts. I will be patient.