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.