[PATCH] nvme: Add support for NVMe 1.3 Timestamp Feature

[hch@lst.de (Christoph Hellwig)]

On Wed, Jul 12, 2017@04:11:01PM -0600, Jon Derrick wrote:
> NVME's Timestamp feature allows controllers to be aware of the epoch
> time in milliseconds. This patch adds the set features hook for various
> transports. It also wires it up to the pci reset path, so that resets
> and resumes can update the controller as necessary.

Please find a way to do this entirely from common code, currently you
miss out on all the non-PCIe transports.

> +	u64 cur_ms;
> +	u8 ts[8] = { 0, };
> +	int status;
> +	u32 result;
> +
> +	cur_ms = ktime_to_ms(ktime_get_real());
> +	put_unaligned_le64(cur_ms, &ts[0]);
> +
> +	status = nvme_set_features(ctrl, NVME_FEAT_TIMESTAMP, 0, ts, 8,

I think this could simply be something like:

	__le64 ts;

	ts = cpu_to_le64(ktime_to_ms(ktime_get_real()));
	status = nvme_set_features(ctrl, NVME_FEAT_TIMESTAMP, 0, &ts,
			sizeof(ts),

> +			&result);
> +	if (status < 0)
> +		dev_warn_once(ctrl->device,
> +			"could not set timestamp (%08x)\n", result);
> +}

The Timestamp feature does not define a result, so you should just
pass NULL for the result parameter.  And if you want to print something
on error the status value is probably more useful.

> +	if (dev->ctrl.vs >= NVME_VS(1, 3, 0) &&
> +	    dev->ctrl.oncs & NVME_CTRL_ONCS_TIMESTAMP)
> +		nvme_set_timestamp(&dev->ctrl);

No need to check for the version - NVMe TPs also apply to all previous
versions if they are backwards compatible, which this one is.