RADEON_MEM_CNTL
tmp = RREG32(RADEON_MEM_CNTL);
tmp = RREG32(RADEON_MEM_CNTL);
temp = RREG32(RADEON_MEM_CNTL);
tmp = RREG32(RADEON_MEM_CNTL);
if (RREG32(RADEON_MEM_CNTL) &
mem_cntl = RREG32(RADEON_MEM_CNTL);
WREG32(RADEON_MEM_CNTL, mem_cntl);
RREG32(RADEON_MEM_CNTL);
WREG32(RADEON_MEM_CNTL, mem_cntl);