Re: [PATCH] nvme/pci: Use host managed power state for suspend

[Sagi Grimberg]

> > +int nvme_set_power(struct nvme_ctrl *ctrl, unsigned ps)
> > +{
> > +	return nvme_set_features(ctrl, NVME_FEAT_POWER_MGMT, ps, NULL, 0, NULL);
> > +}
> > +EXPORT_SYMBOL_GPL(nvme_set_power);
> > +
> > +int nvme_get_power(struct nvme_ctrl *ctrl, u32 *result)
> > +{
> > +	struct nvme_command c;
> > +	union nvme_result res;
> > +	int ret;
> > +
> > +	if (!result)
> > +		return -EINVAL;
> > +
> > +	memset(&c, 0, sizeof(c));
> > +	c.features.opcode = nvme_admin_get_features;
> > +	c.features.fid = cpu_to_le32(NVME_FEAT_POWER_MGMT);
> > +
> > +	ret = __nvme_submit_sync_cmd(ctrl->admin_q, &c, &res,
> > +			NULL, 0, 0, NVME_QID_ANY, 0, 0, false);
> > +	if (ret >= 0)
> > +		*result = le32_to_cpu(res.u32);
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(nvme_get_power);
>
> At this point I'd rather see those in the PCIe driver.  While the
> power state feature is generic in the spec I don't see it actually
> being used anytime anywhere else any time soon.
>
> But maybe we can add a nvme_get_features helper ala nvme_set_features
> in the core to avoid a little boilerplate code for the future?

+1 on this comment.