[PATCH] nvme: associate stripe size quirk with D4512

[David Fugate]

On Mon, 2020-06-15 at 09:20 +0200, Christoph Hellwig wrote:
> On Fri, Jun 12, 2020 at 08:43:15AM -0600, David Fugate wrote:
> > On Thu, 2020-06-11 at 07:41 +0200, Christoph Hellwig wrote:
> > > On Wed, Jun 10, 2020 at 09:38:36PM -0600, David Fugate wrote:
> > > > Intel's D4512 dual-port SSD is based on the older Intel P4500
> > > > SSDs
> > > > whose development predated the NOIOB feature. Based on a
> > > > customer
> > > > request, the D4512's device ID was changed from the P4500s'.
> > > > This
> > > > patch associates D4512's device ID with the stripe size quirk
> > > > to
> > > > improve its performance.
> > > 
> > > NAK.  We've been told Intel forever that we need a standard
> > > quirk,
> > > and we actually do have way to expose this information in
> > > Identify
> > > now.
> > > Just kick your firmware engineers in the but to set the trivial
> > > field
> > > in Identify.
> > 
> > Thanks for the feedback Christoph. Our FW engineer for this product
> > is
> > currently on vacation, but I'll relay your suggestion to see if
> > it's
> > viable.
> > 
> > In the meantime, I'm hearing your rejection for this is simply
> > Intel
> > standardized the driver-assisted striping feature as NOIOB and
> > failed
> > to realize it in any Intel product. Other than this, was there a
> > technical reason for rejecting this patch?
> 
> If you look back in the archives we have been unhappy with this quirk
> for
> years and thus helped to standardize it.  So we very much expect
> Intel to
> use the standard way to any new product instead of adding more and
> more
> quirks.

That's fair feedback. Did hear from our D4512 team there are concerns
with this drive advertising itself as NVMe 1.2 compliant while also
implementing aspects of NVMe 1.3 such as NOIOB. Of course the Linux
NVMe driver does the right thing in terms of ignoring the drive-
reported spec compliance value in favor of feature detection. Can't be
certain that's the case with all other OSes and closed-source drivers
in particular. No final word from that FW team yet. In the meantime,
I've submitted a separate patch to document marketing names of Intel
drives requiring these quirks.

BTW - Intel's recently announced P5500/P5600 product line implements
NOIOB per the spec. It's just these old controllers we're having
problems with.