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

* Luis R. Rodriguez [off-list ref] wrote:

On Wed, Jul 08, 2015 at 06:54:11PM -0700, Luis R. Rodriguez wrote:

quoted

From: "Luis R. Rodriguez" <redacted>

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@pd.tnic
[1] http://lkml.kernel.org/r/20150707095012.GQ7021@wotan.suse.de

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