Re: PCI device function not being enumerated [Was: PCMCIA not working on Panasonic Toughbook CF-29]

From: Ulf Hansson <ulf.hansson@linaro.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: "Michael ." <keltoiboy@gmail.com>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	Linux PCI <linux-pci@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Trevor Jacobs <trevor_jacobs@aol.com>,
	Kris Cleveland <tridentperfusion@yahoo.com>,
	Jeff <bluerocksaddles@willitsonline.com>,
	Morgan Klym <moklym@gmail.com>,
	Philip Langdale <philipl@overt.org>,
	Pierre Ossman <pierre@ossman.eu>,
	Maxim Levitsky <maximlevitsky@gmail.com>,
	"linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>
Subject: Re: PCI device function not being enumerated [Was: PCMCIA not working on Panasonic Toughbook CF-29]
Date: Tue, 25 Feb 2020 16:03:32 +0100	[thread overview]
Message-ID: <CAPDyKFq_exHufHyibFCjS78PTZ7duS9ZSt3vi18CNM6+jMmwnw@mail.gmail.com> (raw)
In-Reply-To: <20200222165617.GA207731@google.com>

On Sat, 22 Feb 2020 at 17:56, Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Tue, Oct 29, 2019 at 12:02:50PM -0500, Bjorn Helgaas wrote:
> > [+cc Ulf, Philip, Pierre, Maxim, linux-mmc; see [1] for beginning of
> > thread, [2] for problem report and the patch Michael tested]
> >
> > On Tue, Oct 29, 2019 at 07:58:27PM +1100, Michael . wrote:
> > > Bjorn and Dominik.
> > > I am happy to let you know the patch did the trick, it compiled well
> > > on 5.4-rc4 and my friends in the CC list have tested the modified
> > > kernel and confirmed that both slots are now working as they should.
> > > As a group of dedicated Toughbook users and Linux users please accept
> > > our thanks your efforts and assistance is greatly appreciated.
> > >
> > > Now that we know this patch works what kernel do you think it will be
> > > released in? Will it make 5.4 or will it be put into 5.5 development
> > > for further testing?
> >
> > That patch was not intended to be a fix; it was just to test my guess
> > that the quirk might be related.
> >
> > Removing the quirk solved the problem *you're* seeing, but the quirk
> > was added in the first place to solve some other problem, and if we
> > simply remove the quirk, we may reintroduce the original problem.
> >
> > So we have to look at the history and figure out some way to solve
> > both problems.  I cc'd some people who might have insight.  Here are
> > some commits that look relevant:
> >
> >   5ae70296c85f ("mmc: Disabler for Ricoh MMC controller")
> >   03cd8f7ebe0c ("ricoh_mmc: port from driver to pci quirk")
> >
> >
> > [1] https://lore.kernel.org/r/CAFjuqNi+knSb9WVQOahCVFyxsiqoGgwoM7Z1aqDBebNzp_-jYw@mail.gmail.com/
> > [2] https://lore.kernel.org/r/20191021160952.GA229204@google.com/
>
> I guess this problem is still unfixed?  I hate the fact that we broke
> something that used to work.
>
> Maybe we need some sort of DMI check in ricoh_mmc_fixup_rl5c476() so
> we skip it for Toughbooks?  Or maybe we limit the quirk to the
> machines where it was originally needed?

Both options seems reasonable to me. Do you have time to put together a patch?

Kind regards
Uffe