Re: [Xen-devel] [PATCH v9 0/8] pci: add pci_iomap_wc() and pci_ioremap_wc_bar()

[Ingo Molnar <mingo@xxxxxxxxxx>]

* Luis R. Rodriguez <mcgrof@xxxxxxxx> wrote:

> On Wed, Jul 08, 2015 at 06:54:11PM -0700, Luis R. Rodriguez wrote:
> > From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx>
> > 
> > Ingo,
> > 
> > Boris is on vacation, he picked up these patches on his bp#tip-mm tree [0]
> > and they have baked there for a while now. That tree receives 0-day
> > bot testing, but other than that its not clear what other tests were
> > run on these patches. Boris modified the commit logs a bit, and made one
> > optimizaiton to bail early on an PCI ioremap call when it should. These
> > patches have no modifications from what is on Boris' tree and tip-mm branch.
> > 
> > The 0 day build bot did find issues on Boris' tree but those are related
> > to ioremap_uc() (already upstream) and its first use on atyfb (not
> > upstream) -- I will be addressing a fix for that ioremap_uc() issue through
> > another patch series prior to posting the final set for atyfb which makes
> > use of ioremap_uc().
> > 
> > No issues have been found with this series. Benh did note some possible 
> > issues
> > with expectations with what is done for write-combining for PowerPC [1] but
> > the issue is a rather general long standing issue with semantics of ioremap 
> > --
> > in the case for ioremap_wc() on PowerPC benh notes that writel() will never
> > write-combine as it uses too heavy barriers. Benh notes that although
> > writel_relaxed() today is identical to writel() this can be changed. There 
> > are
> > other general semantics issues with ioremap() variant calls -- we seem to 
> > have
> > all gotten together to discuss all these issues on a thread where Dan 
> > Williams
> > is proposing to "unify ioremap prototypes and macro aliases" [1], folks
> > intersted on these issues or semantic concerns can drop in and chime there.
> > 
> > Let me know if these are OK or if there are any questions.
> > 
> > [0] http://lkml.kernel.org/r/20150625204703.GC4898@xxxxxxx
> > [1] http://lkml.kernel.org/r/20150707095012.GQ7021@xxxxxxxxxxxxx
> 
> Ingo,
> 
> Just a friendly reminder. Let me know if there are any issues or questions.

It would be nice to get an Acked-by from Bjorn for the PCI API bits.

Thanks,

        Ingo

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