I completed my Qualcomm interview yesterday.

Initial Screening:
3 coding questions related to linked lists, string manipulation, and math.

Onsite:
1st Round: Some OS-related questions like thread vs. process, C++ data structure-related questions, and 4 small (easy-to-medium) coding problems.
2nd Round: Questions on multithreading concepts, virtual vs. physical memory, and a few coding problems.
3rd Round: Questions on mutexes and their implementation, plus coding questions on stack and queue.
4th Round: I was grilled on one of my projects and asked one coding question on backtracking.