PCI Bus Master on MIPS platform

Hi, I'm currently writing a simple test to bus master graphic data from system memory to video memory using ATI's graphic chip. I set the descriptor tables and data in system memory using malloc and assert the correct graphic chip registers to initaiate the bus master, but the data doesn't get transfered.

I enabled the Bus master bit in the PCI config space header, it seems like the graphic chip doesn't know where to fetch the data since the address provided by Malloc functions return the virtual address, where the graphic chip is expecting the physical address. I also tried hardcoding the physical address of the NEC VR5000 chip into the registers but the data doesn't get transferred, It works on a PC platform using DPMI functions which translate logical to physical address. Is there some sort of similar functions for the MIPS platform where I can allocate a pool of system memory that maps virtual to physical address?.