Messages in this thread | | | Subject | Re: [PATCH v3] nvme-pci: Support shared tags across queues for Apple 2018 controllers | From | Benjamin Herrenschmidt <> | Date | Tue, 30 Jul 2019 13:28:57 -0700 |
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On Tue, 2019-07-30 at 09:30 -0600, Keith Busch wrote: > On Fri, Jul 19, 2019 at 03:31:02PM +1000, Benjamin Herrenschmidt wrote: > > From 8dcba2ef5b1466b023b88b4eca463b30de78d9eb Mon Sep 17 00:00:00 2001 > > From: Benjamin Herrenschmidt <benh@kernel.crashing.org> > > Date: Fri, 19 Jul 2019 15:03:06 +1000 > > Subject: > > > > Another issue with the Apple T2 based 2018 controllers seem to be > > that they blow up (and shut the machine down) if there's a tag > > collision between the IO queue and the Admin queue. > > > > My suspicion is that they use our tags for their internal tracking > > and don't mix them with the queue id. They also seem to not like > > when tags go beyond the IO queue depth, ie 128 tags. > > > > This adds a quirk that marks tags 0..31 of the IO queue reserved > > > > Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> > > --- > > One problem is that we've an nvme parameter, io_queue_depth, that a user > could set to something less than 32, and then you won't be able to do > any IO. I'd recommend enforce the admin queue to QD1 for this device so > that you have more potential IO tags.
So I had a look and it's not that trivial. I would have to change a few things that use constants for the admin queue depth, such as the AEN tag etc...
For such a special case, I am tempted instead to do the much simpler:
if (dev->ctrl.quirks & NVME_QUIRK_SHARED_TAGS) { if (dev->q_depth < (NVME_AQ_DEPTH + 2)) dev->q_depth = NVME_AQ_DEPTH + 2; }
In nvme_pci_enable() next to the existing q_depth hackery for other controllers.
Thoughts ?
Cheers, Ben.
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