[PATCH 0/6] ARM: mvebu: mvebu-mbus and I/O coherency fixes
andrew at lunn.ch
Sat Jan 10 09:16:52 PST 2015
On Sat, Jan 10, 2015 at 05:50:30PM +0100, Thomas Petazzoni wrote:
> Dear Andrew Lunn,
> On Sat, 10 Jan 2015 17:30:01 +0100, Andrew Lunn wrote:
> > Fixing window 13 is a big fix. It is getting late in the -rc cycle,
> > which is partially my responsibility, since i was waiting for some
> > tested-by:'s. But these patches are also heading towards
> > stable. Stable rules state:
> > - It must be obviously correct and tested.
> > - It cannot be bigger than 100 lines, with context.
> > - It must fix only one thing.
> > - It must fix a real bug that bothers people (not a, "This could be a
> > problem..." type thing).
> > - It must fix a problem that causes a build error (but not for things
> > marked CONFIG_BROKEN), an oops, a hang, data corruption, a real
> > security issue, or some "oh, that's not good" issue. In short, something
> > critical.
> > The first patch is over 300 lines. Because of its size, i'm also not
> > able to say it is obviously correct. It does however tick some of the
> > other boxes, fix only one thing, fixes a real problem.
> > Is there a more minimal fix? How big an impact is there in just
> > disabling window 13? How much pressure do we have on windows? Can
> > Michal Mazur live with one less window?
> > We could then pushing this proper fix into the next merge window?
> I believe pushing the proposed fix for the next merge window, and
> having a simpler fix that consists in simply not using window 13 for
> stable is a reasonable approach.
Thanks for this. I will pull the two patches into soc today and into
mvebu/linux-next for some testing.
> > For the IO Coherency fixes, obviousness is an issue. This is
> > especially true since your own comment is "still not working 100%
> > properly, but it is apparently not worse than it was."
> > Maybe the correct fix for stable is to simply disable the I/O
> > coherency hardware. That at least makes mainline stable. Once we have
> > a real, well tested, 100% fix, take it via the normal merge window.
> However, I'm not a big fan of this idea. I'd really like to have I/O
> coherency progressively improved, and made working.
> The patch is actually make the code *simpler* since it removes the
> custom dma_map_ops and uses a set of operations that already exists in
> the kernel. The changes in the mvebu-mbus driver are minimal.
Yes, the second patch is a lot of removal of code, which is always
But i would still like comments from others.
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