Message-ID: <20160108203102.GH5354@localhost>
Date:	Fri, 8 Jan 2016 14:31:02 -0600
From:	Bjorn Helgaas <helgaas@...nel.org>
To:	Paul Gortmaker <paul.gortmaker@...driver.com>
Cc:	Arnd Bergmann <arnd@...db.de>,
	Thierry Reding <thierry.reding@...il.com>,
	Ley Foon Tan <lftan@...era.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	linux-pci <linux-pci@...r.kernel.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Pratyush Anand <pratyush.anand@...il.com>,
	Michal Simek <michal.simek@...inx.com>,
	Kishon Vijay Abraham I <kishon@...com>,
	Murali Karicheri <m-karicheri2@...com>,
	Sören Brinkmann <soren.brinkmann@...inx.com>,
	Jason Cooper <jason@...edaemon.net>,
	Stephen Warren <swarren@...dotorg.org>,
	Simon Horman <horms@...ge.net.au>, linux-tegra@...r.kernel.org,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Richard Zhu <Richard.Zhu@...escale.com>,
	Rocketboard Maillist <rfi@...ts.rocketboards.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Lucas Stach <l.stach@...gutronix.de>
Subject: Re: [PATCH 00/10] drivers/pci: avoid module_init in non-modular
 host/pci*

On Tue, Dec 15, 2015 at 10:16:24AM -0500, Paul Gortmaker wrote:
> [Re: [PATCH 00/10] drivers/pci: avoid module_init in non-modular host/pci*] On 14/12/2015 (Mon 11:27) Arnd Bergmann wrote:
> 
> > On Monday 14 December 2015 10:19:40 Thierry Reding wrote:
> > > > PCIe host driver that use fixup (DECLARE_PCI_FIXUP_*) can't use tristate.
> > > > Fixup region is in kernel region and this region if not updated when
> > > > loading a module.
> > > 
> > > Interesting, I hadn't thought about that. I suppose this means that the
> > > module will end up containing an unused section with the fixup code. It
> > > might be useful to add a way for that to trigger a warning at build
> > > time.
> > > 
> > > Perhaps to fix this a mechanism could be introduced to add a table of
> > > fixups to a host controller driver and that will get applied to all
> > > children of the bridge. It could be problematic to cover all of the
> > > different fixup stages, though.
> > 
> > I think a lot of the fixups shouldn't really be there in the first place,
> > they are about stuff that we can fix up in the probe function, or that should
> > be fixed up in the probe function with some appropriate core support added.
> 
> So, the feedback on this is a bit all over the map, leaving me unsure
> what to do next.  And is the choice we make on a per board/bsp basis or
> ideally across all platforms?  I see the choices as:
> 
> 1) do nothing; which IMHO is least desirable as it leaves the code
> misrepresenting itself as modular; one of the key issues I wanted to fix
> 
> 2) use the patches I've sent ; then as they are genuinely made modular,
> the person doing so essentially "patch -R" or reverts the change as
> step one.  This has the advantage of solving the "we'll get to it
> someday" issue if someday never comes.
> 
> 3) make them all tristate;  beat it with a stick until it compiles [M]
> and modposts -- leaving the fixups and functional testing to people with
> the boards and low level knowledge to make it _work_ as a module.  The
> downside here is the code is still kind of misrepresenting itself as
> modularly functional -- a ban of unloading might mitigate that some.

I'd like to preserve the mind-set that host controller drivers are
*expected* to be modular, even if we aren't there yet.  I guess that
means I'm in favor of option 3, at least for drivers that don't use
fixups.

Bjorn

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