linux-kernel - Re: [PATCH] bcma: Fix 'allmodconfig' and BCMA builds on MIPS targets

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Message-ID: <20180115171053.6nvstoufw4y6ar4s@pburton-laptop>
Date:   Mon, 15 Jan 2018 09:10:53 -0800
From:   Paul Burton <paul.burton@...s.com>
To:     James Hogan <jhogan@...nel.org>, Guenter Roeck <linux@...ck-us.net>
CC:     Rafał Miłecki <zajec5@...il.com>,
        <linux-wireless@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Matt Redfearn" <matt.redfearn@...tec.com>
Subject: Re: [PATCH] bcma: Fix 'allmodconfig' and BCMA builds on MIPS targets

Hello,

On Mon, Jan 15, 2018 at 10:23:37AM +0000, James Hogan wrote:
> On Sun, Jan 14, 2018 at 01:34:02PM -0800, Guenter Roeck wrote:
> > Mips builds with BCMA host mode enabled fail in mainline and -next
> > with:
> > 
> > In file included from include/linux/bcma/bcma.h:10:0,
> >                  from drivers/bcma/bcma_private.h:9,
> > 		 from drivers/bcma/main.c:8:
> > include/linux/bcma/bcma_driver_pci.h:218:24: error:
> > 	field 'pci_controller' has incomplete type
> > 
> > Bisect points to commit d41e6858ba58c ("MIPS: Kconfig: Set default MIPS
> > system type as generic") as the culprit. Analysis shows that the commmit
> > changes PCI configuration and enables PCI_DRIVERS_GENERIC. This in turn
> > disables PCI_DRIVERS_LEGACY. 'struct pci_controller' is, however, only
> > defined if PCI_DRIVERS_LEGACY is enabled.
> > 
> > Ultimately that means that BCMA_DRIVER_PCI_HOSTMODE depends on
> > PCI_DRIVERS_LEGACY. Add the missing dependency.
> > 
> > Fixes: d41e6858ba58c ("MIPS: Kconfig: Set default MIPS system type as ...")
> 
> Well, technically I think commit c5611df96804 ("MIPS: PCI: Introduce
> CONFIG_PCI_DRIVERS_LEGACY") is to blame (Cc'ing paul), and the first bad
> commit would be commit eed0eabd12ef ("MIPS: generic: Introduce generic
> DT-based board support") which selects PCI_DRIVERS_GENERIC and is the
> only platform to do so. Both commits were first in v4.9-rc1 and I can
> reproduce this problem at that latter commit with the appropriate
> configuration.

Ah - yes if I recall correctly my assumption was that the MIPS-specific
struct pci_controller was only used by the MIPS-specific PCI drivers
under arch/mips/pci/, which are only built when configured for the
appropriate platform.

In this case use of that MIPS-specific struct pci_controller has spread
beyond arch/mips/ & the user can be configured in for platforms other
than the one that will actually use the driver, including the generic
platform which moves towards more generic PCI drivers in
drivers/pci/host/.

> But yes clearly the mentioned commit does also expose that existing
> problem more widely and to the default allmodconfig, and it looks like a
> reasonable approach for now, so if some mention of the other two commits
> is added:
> 
> Reviewed-by: James Hogan <jhogan@...nel.org>

Likewise, with the "Fixes:" tag fixed:

    Reviewed-by: Paul Burton <paul.burton@...s.com>

Thanks,
    Paul

> Having it in 4.15 would be great.
> 
> Cheers
> James
> 
> > Cc: Matt Redfearn <matt.redfearn@...tec.com>
> > Cc: James Hogan <jhogan@...nel.org>
> > Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> > ---
> > I am aware that this problem has been reported several times. I have
> > not been able to find a fix, but I may have missed it. If so, my
> > apologies for the noise.
> > 
> > Also note that this is not the only fix required; commit d41e6858ba58c,
> > as simple as it looks like, does a pretty good job messing up
> > "mips:allmodconfig" builds.
> > 
> >  drivers/bcma/Kconfig | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/bcma/Kconfig b/drivers/bcma/Kconfig
> > index 02d78f6cecbb..ba8acca036df 100644
> > --- a/drivers/bcma/Kconfig
> > +++ b/drivers/bcma/Kconfig
> > @@ -55,7 +55,7 @@ config BCMA_DRIVER_PCI
> >  
> >  config BCMA_DRIVER_PCI_HOSTMODE
> >  	bool "Driver for PCI core working in hostmode"
> > -	depends on MIPS && BCMA_DRIVER_PCI
> > +	depends on MIPS && BCMA_DRIVER_PCI && PCI_DRIVERS_LEGACY
> >  	help
> >  	  PCI core hostmode operation (external PCI bus).
> >  
> > -- 
> > 2.7.4
> >