regSDMA_GFX_RB_WPTR_POLL_CNTL
wptr_poll_cntl = RREG32_SDMA(i, regSDMA_GFX_RB_WPTR_POLL_CNTL);
WREG32_SDMA(i, regSDMA_GFX_RB_WPTR_POLL_CNTL, wptr_poll_cntl);