Re: [PATCH v2 2/6] PCI/MSI: Factor out pci_get_msi_cap() interface

From: Bjorn Helgaas
Date: Fri Sep 06 2013 - 19:32:22 EST


On Fri, Sep 06, 2013 at 12:06:21PM -0400, Tejun Heo wrote:
> Hello, Bjorn.
>
> On Fri, Sep 06, 2013 at 10:01:38AM -0600, Bjorn Helgaas wrote:
> > Sorry, I haven't jumped in here yet because I saw your discussion and
> > was hoping you guys would figure something out without my help. It
> > will take me a few hours to look into this and come up with anything
> > constructive to say.
> >
> > I do remember disliking the complicated interface of
> > pci_enable_msi_block() (return negative errno, return positive "we
> > might be able to do this" values, or zero), but I'll have to do some
> > more research before I can say much more than that.
>
> According to Alexander, it doesn't even seem like we have any actual
> use case for the positive return numbers. I say just rip it out and
> do the regular 0/-errno all the way through.

I agree, that would be much simpler.

I propose that you rework it that way, and at least find out what
(if anything) would break if we do that. Or maybe we just give up
some optimization; it would be nice to quantify that, too.

Bjorn
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