DBUF_POWER_STATE
state = intel_de_read(display, reg) & DBUF_POWER_STATE;
if (intel_de_read(display, DBUF_CTL_S(slice)) & DBUF_POWER_STATE)
vgpu_vreg(vgpu, offset) |= DBUF_POWER_STATE;
vgpu_vreg(vgpu, offset) &= ~DBUF_POWER_STATE;