[PATCH v3] nvme: add quirk to force medium priority for SQ creation

[Keith Busch]

On Tue, May 08, 2018 at 09:40:14PM -0700, Christoph Hellwig wrote:
> On Tue, May 08, 2018 at 10:25:15AM -0600, Jens Axboe wrote:
> > Some P3100 drives have a bug where they think WRRU (weighted round
> > robin) is always enabled, even though the host doesn't set it. Since
> > they think it's enabled, they also look at the submission queue
> > creation priority. We used to set that to MEDIUM by default,
> > but that was removed in commit 81c1cd98351b. This causes various
> > issues on that drive. Add a quick to still set MEDIUM priority
> > for that controller.
> 
> And this really isn't something that could be fixed with a trivial
> firmware uptodate?  I'd really hate to pile on hacks like this if we
> can somehow avoid it.

Agreed, we don't like resorting to this option; we have only 32 entries
in the quirk table before we're out of bits. In this case, though, all
device side options for this issue were explored before considering a
driver-side work-around.