From: Michael Ellerman <michael@ellerman.id.au>
To: Anton Blanchard <anton@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org, paulus@samba.org
Subject: Re: [PATCH] powerpc: pseries: Round up MSI-X requests
Date: Wed, 13 Jun 2012 15:18:07 +1000 [thread overview]
Message-ID: <1339564687.8742.9.camel@concordia> (raw)
In-Reply-To: <20120605124703.12bb4cc3@kryten>
On Tue, 2012-06-05 at 12:47 +1000, Anton Blanchard wrote:
> Hi,
>
> > On Mon, 2012-06-04 at 16:43 +1000, Michael Ellerman wrote:
> > > There is some chance this will result in breakage because the driver
> > > asks for N - and assumes that is what was allocated - and the
> > > device is configured for > N.
> >
> > We can fix that. We can whack the configuration back with N, just know
> > that we have "allocated" > N.
I think whacking config space is more likely to break something than
just configuring more than the driver asked for.
> I agree we don't want to be giving back a larger value than requested.
> There's only one place that can happen in theory and since firmware only
> returns power of two values I dont think it will happen in practise.
Don't follow you here.
> Even so do we want to do something like this (as yet untested)? If the
> rounded up request fails we retry with the original request.
Yes we do. Had a chance to test it?
> The pseries msi free code just sets our vectors to 0 so it doesn't need
> to know how many were originally allocated.
Yep, looks like it will cope.
We only create virqs for what's in pdev->msi_list, which will be what
the driver originally asked for, and we free all those by walking the
list again. So the fact that firmware allocated a few extra for us is
OK, we have nothing extra to cleanup.
cheers
next prev parent reply other threads:[~2012-06-13 5:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-03 23:15 [PATCH] powerpc: pseries: Round up MSI-X requests Anton Blanchard
2012-06-04 6:43 ` Michael Ellerman
2012-06-04 6:54 ` Benjamin Herrenschmidt
2012-06-05 2:47 ` Anton Blanchard
2012-06-13 5:18 ` Michael Ellerman [this message]
2012-06-13 5:25 ` Benjamin Herrenschmidt
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