netdev - Re: [PATCH RFC 00/77] Re-design MSI/MSI-X interrupts enablement pattern

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Date:	Thu, 10 Oct 2013 20:07:05 +0200
From:	Alexander Gordeev <agordeev@...hat.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Michael Ellerman <michael@...erman.id.au>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Ingo Molnar <mingo@...hat.com>, Tejun Heo <tj@...nel.org>,
	Dan Williams <dan.j.williams@...el.com>,
	Andy King <acking@...are.com>, Jon Mason <jon.mason@...el.com>,
	Matt Porter <mporter@...nel.crashing.org>,
	linux-pci@...r.kernel.org, linux-mips@...ux-mips.org,
	linuxppc-dev@...ts.ozlabs.org, linux390@...ibm.com,
	linux-s390@...r.kernel.org, x86@...nel.org,
	linux-ide@...r.kernel.org, iss_storagedev@...com,
	linux-nvme@...ts.infradead.org, linux-rdma@...r.kernel.org,
	netdev@...r.kernel.org, e1000-devel@...ts.sourceforge.net,
	linux-driver@...gic.com,
	Solarflare linux maintainers <linux-net-drivers@...arflare.com>,
	"VMware, Inc." <pv-drivers@...are.com>, linux-scsi@...r.kernel.org
Subject: Re: [PATCH RFC 00/77] Re-design MSI/MSI-X interrupts enablement
 pattern

On Thu, Oct 10, 2013 at 09:28:27AM -0700, H. Peter Anvin wrote:
> On 10/10/2013 03:17 AM, Alexander Gordeev wrote:
> > On Wed, Oct 09, 2013 at 03:24:08PM +1100, Benjamin Herrenschmidt wrote:
> > 
> > Ok, this suggestion sounded in one or another form by several people.
> > What about name it pcim_enable_msix_range() and wrap in couple more
> > helpers to complete an API:
> > 
> > int pcim_enable_msix_range(pdev, msix_entries, nvec, minvec);
> > 	<0 - error code
> > 	>0 - number of MSIs allocated, where minvec >= result <= nvec
> > 
> > int pcim_enable_msix(pdev, msix_entries, nvec);
> > 	<0 - error code
> > 	>0 - number of MSIs allocated, where 1 >= result <= nvec 
> > 
> > int pcim_enable_msix_exact(pdev, msix_entries, nvec);
> > 	<0 - error code
> > 	>0 - number of MSIs allocated, where result == nvec
> > 
> > The latter's return value seems odd, but I can not help to make
> > it consistent with the first two.
> > 
> 
> Is there a reason for the wrappers, as opposed to just specifying either
> 1 or nvec as the minimum?

The wrappers are more handy IMO.

I.e. can imagine people start struggling to figure out what minvec to provide:
1 or 0? Why 1? Oh.. okay.. Or should we tolerate 0 (as opposite to -ERANGE)?

Well, do not know.. pcim_enable_msix(pdev, msix_entries, nvec, nvec) is 
less readable for me than just pcim_enable_msix_exact(pdev, msix_entries,
nvec).

> 	-hpa

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