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

From: Bjorn Helgaas
Date: Sat Feb 22 2020 - 11:56:21 EST

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]
> [2]

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?