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

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Message-ID: <20100812164557.5f2513a6@virtuousgeek.org>
Date:	Thu, 12 Aug 2010 16:45:57 -0700
From:	Jesse Barnes <jbarnes@...tuousgeek.org>
To:	Dave Airlie <airlied@...il.com>
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, 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?

-- 
Jesse Barnes, Intel Open Source Technology Center
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