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Date:   Sat, 22 Feb 2020 10:56:17 -0600
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     "Michael ." <keltoiboy@gmail.com>
Cc:     Dominik Brodowski <linux@dominikbrodowski.net>,
        linux-pci@vger.kernel.org, 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>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Philip Langdale <philipl@overt.org>,
        Pierre Ossman <pierre@ossman.eu>,
        Maxim Levitsky <maximlevitsky@gmail.com>,
        linux-mmc@vger.kernel.org
Subject: Re: PCI device function not being enumerated [Was: PCMCIA not
 working on Panasonic Toughbook CF-29]
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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?

Bjorn