linux-kernel - Re: [TIP,regression,i915] /dev/dri/card0 is no longer present

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Message-Id: <1236030235.4586.79.camel@localhost.localdomain>
Date:	Mon, 02 Mar 2009 13:43:55 -0800
From:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Sitsofe Wheeler <sitsofe@...oo.com>,
	"dri-devel@...ts.sourceforge.net" <dri-devel@...ts.sourceforge.net>,
	LKML <linux-kernel@...r.kernel.org>,
	"Siddha, Suresh B" <suresh.b.siddha@...el.com>,
	Jesse Barnes <jbarnes@...tuousgeek.org>
Subject: Re: [TIP,regression,i915] /dev/dri/card0 is no longer present

On Mon, 2009-03-02 at 13:34 -0800, Ingo Molnar wrote:
> * Pallipadi, Venkatesh <venkatesh.pallipadi@...el.com> wrote:
> 
> > On Sun, 2009-03-01 at 05:48 -0800, Sitsofe Wheeler wrote:
> > > On Sun, Mar 01, 2009 at 12:39:48PM +0100, Ingo Molnar wrote:
> > > >
> > > > Thanks, i've reverted the commit for now. Could you please send
> > > > a 'dmesg' from the bootup with the failed driver? By all
> > > > likelyhood an ioremap failure causes a driver failure.
> > > >
> > > 
> > > See below (drm says it initalized though...):
> > > 
> > > [    0.000000] Linux version 2.6.29-rc6-00006-g17581ad (@verona) (gcc version 4.2.4) #87 Sun Mar 1 13:42:28 GMT 2009
> > > [    0.000000] KERNEL supported cpus:
> > > [    0.000000]   Intel GenuineIntel
> > > [    0.000000] PAT WC disabled due to known CPU erratum.
> > 
> > Looks like PAT is getting disabled on this platform. Can you 
> > send the output of /proc/cpuinfo please.
> 
> Does this mean we failed an ioremap()? We still should not fail 
> a device ioremap _ever_. We should just fall back to UC and be 
> done with it. We may emit a warning if we consider it 
> troublesome, but we should never ever break working drivers 
> really.
> 

No. We don't break ioremap. We try to fallback on UC_MINUS here. But,
there is something wrong happening in that path, that is resulting in
this issue. I am looking at that right now.

I have found another problem with this particular patch, on one of test
systems. So, let us keep the revert until I fix what looks like two
different problems here.

Thanks,
Venki

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