linux-kernel - Re: [PATCH v2 1/2] pci: prevent sk hynix nvme from entering D3

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Date:   Thu, 15 Nov 2018 11:30:15 -0600
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Kai Heng Feng <kai.heng.feng@...onical.com>
Cc:     AceLan Kao <acelan.kao@...onical.com>,
        Keith Busch <keith.busch@...el.com>, Jens Axboe <axboe@...com>,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pci@...r.kernel.org
Subject: Re: [PATCH v2 1/2] pci: prevent sk hynix nvme from entering D3

On Thu, Nov 15, 2018 at 08:58:09AM -0600, Bjorn Helgaas wrote:
> On Thu, Nov 15, 2018 at 03:16:29PM +0800, Kai Heng Feng wrote:
> > On Nov 9, 2018, at 08:21, Bjorn Helgaas <helgaas@...nel.org> wrote:

> > > I'm not sure we want a quirk for this at all, since as Christoph
> > > points out, it doesn't fix a functional issue as the other uses of
> > > quirk_no_ata_d3() do.
> > > 
> > > From your emails with Christoph, it sounds like this quirk is a
> > > workaround for a firmware defect.  If we *do* end up wanting a quirk,
> > > the changelog should at least mention the firmware defect and maybe
> > > check whether it has been fixed.
> > 
> > According to SK Hynix folks and new evidence on the new Intel NVMe
> > we have, this is something we are going to see more often.
> 
> Hmmm, are you suggesting that if we went this quirk route, we'd be
> updating the quirk frequently to add new devices?
> 
> I'm opposed to that as a strategy because it makes needless work.  You
> have to update the quirk, backport it to older kernels, re-release
> distro kernels, etc.

But I guess you have to do this anyway just to add the vendor/device
ID to the driver, so maybe this isn't a big deal to you.  If you can
do a quirk like this in the driver, it would be invisible to me and I
wouldn't care.  I just don't want to deal with ongoing tweaks like
this in the PCI core :)

Bjorn