Hi, Arjuh
I was able to successfully receive/provide SPI data in slave CC2540 device by using two DMA channels (otherwise, tightly packed SPI words make any sort of problem when trying to pass interrupt event to OSAL-managed event loop). However, the CPU core stoppage problem is still here. The good news is that 1.3 stack has an ability to disable this feature and leave the core running. Check out this thread:
http://e2e.ti.com/support/low_power_rf/f/538/t/227515.aspx
BR,
Oleg