static int
nouveau_pm_perflvl_set(struct drm_device *dev, struct nouveau_pm_level *perflvl)
{
	struct drm_nouveau_private *dev_priv = dev->dev_private;
	struct nouveau_pm_engine *pm = &dev_priv->engine.pm;
	uint32_t status;
	int ret;

	if (perflvl == pm->cur)
		return 0;

	if (pm->voltage.supported && pm->voltage_set && perflvl->voltage) {
		ret = pm->voltage_set(dev, perflvl->voltage);
		if (ret) {
			NV_ERROR(dev, "voltage_set %d failed: %d\n",
				 perflvl->voltage, ret);
		}
	}

	/* TODO: Wait for vblank */
	/* Pause the engines, if possible */
	if (dev_priv->engine.fifo.pause(dev)) {
		ret = -EIO;
		goto out;
	}
	if (dev_priv->engine.graph.pause(dev)) {
		ret = -EIO;
		goto out;
	}
	/* Change the clocks */
	nouveau_pm_clock_set(dev, perflvl, PLL_CORE, perflvl->core);
	nouveau_pm_clock_set(dev, perflvl, PLL_SHADER, perflvl->shader);
	nouveau_pm_clock_set(dev, perflvl, PLL_MEMORY, perflvl->memory);
	nouveau_pm_clock_set(dev, perflvl, PLL_UNK05, perflvl->unk05);

	/* Wait for PLLs to stabilize */
	udelay(100);

	pm->cur = perflvl;
	ret = 0;

out:
	/* Un-pause the engines */
	dev_priv->engine.fifo.unpause(dev);
	dev_priv->engine.graph.unpause(dev);

	return ret;
}