VORTEX_MIXER_SR
temp = hwread(vortex->mmio, VORTEX_MIXER_SR);
eax = hwread(vortex->mmio, VORTEX_MIXER_SR);
hwwrite(vortex->mmio, VORTEX_MIXER_SR, 0);
hwwrite(vortex->mmio, VORTEX_MIXER_SR,
hwread(vortex->mmio, VORTEX_MIXER_SR) | (0x1 << channel));
hwwrite(vortex->mmio, VORTEX_MIXER_SR,
hwread(vortex->mmio, VORTEX_MIXER_SR) & ~(0x1 << channel));