Re: Regression caused by commit 882164a4a928

From: "Rafał Miłecki" <zajec5@gmail.com>
To: Larry Finger <Larry.Finger@lwfinger.net>
Cc: "Matt Redfearn" <matt.redfearn@mips.com>,
	"Michael Büsch" <m@bues.ch>, "Kalle Valo" <kvalo@codeaurora.org>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: Regression caused by commit 882164a4a928
Date: Thu, 10 May 2018 12:41:24 +0200	[thread overview]
Message-ID: <CACna6rxb9KSQfGwi__xxSMACAxh-bOV9SR1NsnUVe8ASdA0Liw@mail.gmail.com> (raw)
In-Reply-To: <7bbc067a-c412-3d2e-174a-abc31b46e246@lwfinger.net>

On 7 May 2018 at 17:44, Larry Finger <Larry.Finger@lwfinger.net> wrote:
> Although commit 882164a4a928 ("ssb: Prevent build of PCI host features in
> module") appeared to be harmless, it leads to complete failure of drivers
> b43. and b43legacy, and likely affects b44 as well. The problem is that
> CONFIG_SSB_PCIHOST is undefined, which prevents the compilation of the code
> that controls the PCI cores of the device. See
> https://bugzilla.redhat.com/show_bug.cgi?id=1572349 for details.
>
> As the underlying errors ("pcibios_enable_device" undefined, and
> "register_pci_controller" undefined) do not appear on the architectures that
> I have tested (x86_64, x86, and ppc), I suspect something in the
> arch-specific code for your setup (MIPS?). As I have no idea on how to fix
> that problem, would the following patch work for you?
>
> diff --git a/drivers/ssb/Kconfig b/drivers/ssb/Kconfig
> index 9371651d8017..3743533c8057 100644
> --- a/drivers/ssb/Kconfig
> +++ b/drivers/ssb/Kconfig
> @@ -117,7 +117,7 @@ config SSB_SERIAL
>
>  config SSB_DRIVER_PCICORE_POSSIBLE
>         bool
> -       depends on SSB_PCIHOST && SSB = y
> +       depends on SSB_PCIHOST && (SSB = y || !MIPS)
>         default y
>
>  config SSB_DRIVER_PCICORE

I strongly suggest we take a step back, slow down a bit and look at
the original problem.

In driver_pcicore.c there is MIPS specific code. It's protected using
#ifdef CONFIG_SSB_PCICORE_HOSTMODE
(...)
#endif

If anyone has ever seen
ERROR: "pcibios_enable_device" [drivers/ssb/ssb.ko] undefined!
ERROR: "register_pci_controller" [drivers/ssb/ssb.ko] undefined!
make[1]: *** [scripts/Makefile.modpost:92: __modpost] Error 1
it means he managed to get CONFIG_SSB_PCICORE_HOSTMODE set on non-MIPS system.

We should rather answer how did that happen and fix it.

SSB_PCICORE_HOSTMODE depends on SSB_DRIVER_MIPS
SSB_DRIVER_MIPS depends on MIPS

How is that possible to set SSB_PCICORE_HOSTMODE with non-MIPS config?
Is there some mistake in Kconfig I can't see?

-- 
Rafał