linux-kernel - Re: [PATCH] drm: Fix support for PCI domains

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Message-ID: <AANLkTik+MX8cKz6hWyaa8Z2gK7fehXzjSPpeiyExuMjb@mail.gmail.com>
Date:	Fri, 13 Aug 2010 10:22:17 +1000
From:	Dave Airlie <airlied@...il.com>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
Cc:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	dri-devel@...ts.sourceforge.net,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm: Fix support for PCI domains

On Fri, Aug 13, 2010 at 9:45 AM, Jesse Barnes <jbarnes@...tuousgeek.org> wrote:
> On Fri, 13 Aug 2010 09:33:35 +1000
> Dave Airlie <airlied@...il.com> wrote:
>
>> On Fri, Aug 13, 2010 at 7:30 AM, Geert Uytterhoeven
>> <geert@...ux-m68k.org> wrote:
>> > On Fri, Aug 6, 2010 at 05:55, Benjamin Herrenschmidt
>> > <benh@...nel.crashing.org> wrote:
>> >> (For some reason I thought that went in ages ago ...)
>> >>
>> >> This fixes support for PCI domains in what should hopefully be a backward
>> >> compatible way along with a change to libdrm.
>> >>
>> >> When the interface version is set to 1.4, we assume userspace understands
>> >> domains and the world is at peace. We thus pass proper domain numbers
>> >> instead of 0 to userspace.
>> >>
>> >> The newer libdrm will then try 1.4 first, and fallback to 1.1, along with
>> >> ignoring domains in the later case (well, except on alpha of course)
>> >>
>> >> Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
>> >> ---
>> >>  drivers/gpu/drm/drm_ioctl.c |    1 +
>> >>  include/drm/drmP.h          |   18 +++++++++++++-----
>> >>  include/drm/drm_core.h      |    2 +-
>> >>  3 files changed, 15 insertions(+), 6 deletions(-)
>> >
>> >> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
>> >> index c1b9871..6d4bad5 100644
>> >> --- a/include/drm/drmP.h
>> >> +++ b/include/drm/drmP.h
>> >> @@ -1071,11 +1071,19 @@ static __inline__ int drm_core_check_feature(struct drm_device *dev,
>> >>        return ((dev->driver->driver_features & feature) ? 1 : 0);
>> >>  }
>> >>
>> >> -#ifdef __alpha__
>> >> -#define drm_get_pci_domain(dev) dev->hose->index
>> >> -#else
>> >> -#define drm_get_pci_domain(dev) 0
>> >> -#endif
>> >> +static inline int drm_get_pci_domain(struct drm_device *dev)
>> >> +{
>> >> +#ifndef __alpha__
>> >> +       /* For historical reasons, drm_get_pci_domain() is busticated
>> >> +        * on most archs and has to remain so for userspace interface
>> >> +        * < 1.4, except on alpha which was right from the beginning
>> >> +        */
>> >> +       if (dev->if_version < 0x10004)
>> >> +               return 0;
>> >> +#endif /* __alpha__ */
>> >> +
>> >> +       return pci_domain_nr(dev->pdev->bus);
>> >
>> > error: implicit declaration of function ‘pci_domain_nr’
>> > on m68k without PCI.
>>
>> I don't think I want to add an ifdef CONFIG_PCI into the drm layer for
>> this, since we seem to be okay everywhere else,
>>
>> lets ask jbarnes, not sure if its safe to just add this to the
>> !CONFIG_PCI section of the linux/pci.h
>
> Hm, so pci_domain_nr should just return 0 on platforms where
> CONFIG_PCI_DOMAINS isn't set.  I'd expect that to be the case when
> CONFIG_PCI=n...  Maybe we just need to shuffle the definition around?

I suspect something like the attached would suffice.

Or maybe moving the CONFIG_PCI_DOMAINS checkout outside CONFIG_PCI.

Dave.

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