Re: [PATCH] pci: enable MSI on 8132

From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: david@lang.hm, Matthew Wilcox <matthew@wil.cx>,
	Yinghai Lu <yinghai@kernel.org>,
	Jesse Barnes <jbarnes@virtuousgeek.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-scsi@vger.kernel.org, DL-MPTFusionLinux@lsi.com,
	linux-pci@vger.kernel.org
Subject: Re: [PATCH] pci: enable MSI on 8132
Date: Wed, 18 Feb 2009 18:38:04 +0000	[thread overview]
Message-ID: <1234982285.3225.42.camel@localhost.localdomain> (raw)
In-Reply-To: <20090218100448.7f7c5b86.akpm@linux-foundation.org>

On Wed, 2009-02-18 at 10:04 -0800, Andrew Morton wrote:
> On Wed, 18 Feb 2009 04:27:28 -0800 (PST) david@lang.hm wrote:
> 
> > On Wed, 18 Feb 2009, Matthew Wilcox wrote:
> > 
> > > On Tue, Feb 17, 2009 at 08:40:09PM -0800, Yinghai Lu wrote:
> > >>
> > >> Impact: workaround BIOS that doesn't enable that bit
> > >>
> > >> David reported that LSI sas doesn't work with MSI.
> > >> it turns out that BIOS doesn't enable HT MSI
> > >> 8132 does support HT MSI.
> > >> add quirk to enable it
> > >>
> > >> Reported-by: David Lang <david@lang.hm>
> > >> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> > >
> > > Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
> > >
> > > Jesse, I think this should go into Linus' tree sooner rather than later.
> > 
> > please forward to -stable as well. this is a regression since the card 
> > works with older kernels.
> > 
> 
> Which kernel version introduced the regression?

Technically, it's not a regression.  The MSI problem has always been
there, it was just exposed when the SAS card switched to using MSI by
default.  It's fixed by the bridge quirk  ... of course it's unclear how
many more bridges with problems there are.

> Do we not need mpt-fix-enable-lsi-sas-to-use-msi-as-default.patch as
> well, to fix this regression?

No ... it's a separate issue.  MSI was enabled for fusion SAS in 2.6.26;
the problem msi patch which the above corrects actually has the effect
of disabling MSI for fusion and went into 2.6.29-rc2, which isn't a
kernel that's been tested here.

> I sent mpt-fix-enable-lsi-sas-to-use-msi-as-default.patch to the
> maintainers a week ago and it was ignored, along with everything else. 
> If this happens again I shall merge it under my own cognisance, along
> with everything else.

Yes, they've been a bit unresponsive.   I'm not unhappy with the current
situation, since MSI is globally disabled for fusion at the moment (so
we shouldn't get any more MSI problem reports), so I'm happy to wait and
see what they want to do.

James