mmVCE_RB_RPTR3
WREG32(mmVCE_RB_RPTR3, lower_32_bits(ring->wptr));
v = RREG32(mmVCE_RB_RPTR3);
WREG32(SOC15_REG_OFFSET(VCE, 0, mmVCE_RB_RPTR3), lower_32_bits(ring->wptr));
return RREG32(SOC15_REG_OFFSET(VCE, 0, mmVCE_RB_RPTR3));