linux-kernel - Re: [PATCH v2 2/6] PCI/MSI: Factor out pci_get_msi

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Message-ID: <20130906131739.GA27922@dhcp-26-207.brq.redhat.com>
Date:	Fri, 6 Sep 2013 15:17:40 +0200
From:	Alexander Gordeev <agordeev@...hat.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	linux-kernel@...r.kernel.org, x86@...nel.org,
	linux-pci@...r.kernel.org, linux-ide@...r.kernel.org,
	Ingo Molnar <mingo@...nel.org>, Joerg Roedel <joro@...tes.org>,
	Jan Beulich <JBeulich@...e.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v2 2/6] PCI/MSI: Factor out pci_get_msi_cap() interface

On Thu, Sep 05, 2013 at 05:40:41PM +0200, Alexander Gordeev wrote:
> On Thu, Sep 05, 2013 at 11:04:42AM -0400, Tejun Heo wrote:
> > The thing is, do we even have cases where arch code returns positive
> > return to indicate possible partial allocation?  If not, the whole
> > interface is convoluted for no good reason and we can just make
> > everything return 0 or -errno, which is a lot simpler.  No?
> 
> As I mentioned in my other note, at least PPC has a concept of MSI quota,
> so exceeding it would be the very case, I believe.

An update here. No other arch supports multiple MSIs besides Intel (+IOMMU).
Yet, ironically, the concept of possible partial allocation was adopted from
MSI-X. I briefly checked all archs and it seems none of them throws out a
possible other number of MSIs > 1 (including PPC I mistakenly read).

-- 
Regards,
Alexander Gordeev
agordeev@...hat.com
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