RE: [PATCH] pci: enable MSI on 8132

[Prakash, Sathya]

Apologies for late response on this thread.
Considering the fact that the enabling MSI has issues with some unknown boards we will turn off the MSI for all the type of controllers (including the SAS) and will send the corrected patch soon (with proper module description). Till we find out a way to dynamically decide whether we can enable MSI without any issues, we don't want to set the module parameter to enable MSI by default for SAS controllers.

Thanks
Sathya

-----Original Message-----
From: James Bottomley [mailto:James.Bottomley@xxxxxxxxxxxxxxxxxxxxx] 
Sent: Thursday, February 19, 2009 12:08 AM
To: Andrew Morton
Cc: david@xxxxxxx; Matthew Wilcox; Yinghai Lu; Jesse Barnes; linux-kernel; linux-scsi@xxxxxxxxxxxxxxx; DL-MPT Fusion Linux; linux-pci@xxxxxxxxxxxxxxx
Subject: Re: [PATCH] pci: enable MSI on 8132

On Wed, 2009-02-18 at 10:04 -0800, Andrew Morton wrote:
> On Wed, 18 Feb 2009 04:27:28 -0800 (PST) david@xxxxxxx 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@xxxxxxx>
> > >> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
> > >
> > > Reviewed-by: Matthew Wilcox <willy@xxxxxxxxxxxxxxx>
> > >
> > > 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


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