Well, you never responded to my question about what DPP is, or where you're getting it from, so I have to still go with my original assumption that is it
Windows software from the Canon CD. The chances of it working
really well under Wine are unknown (to me, at this time). If Canon is going to support Linux, that is a question to be asked of Canon.
If it is a work-flow for RAW images you're looking for, there are
many native Linux applications that can handle RAW images, so it becomes a question of getting those images onto your PC. If you cannot transfer them directly from your camera (but can transfer the JPG images, I presume), then I still maintain that a card reader is going to be the easiest solution.
If you're happy with your current workflow with digiKam, then I guess that's it...
Sorry I couldn't be of more help.