On Thu, Aug 09, 2012 at 12:43:35AM +0200, Henrik Rydberg wrote:
> Hi Seth,
> 
> > From: Henrik Rydberg <[email protected]>
> > 
> > commit a332bf9a65ab34b01226ed177f6937af843c8465 upstream.
> > 
> > The 2012 series of MacBooks have a faster SMC, and the current driver
> > timings do not work at all. Tests show that decreasing the minimum
> > wait time, from 64 us to 16 us, works well. Since this is still larger
> > than the original minimum of 10 us used before 2008, there is nothing
> > inherently problematic with changing it. The fail frequency on older
> > machines seems to increase slightly, but not enough to be noticeable.
> > 
> > Tested on MBA11, MBA31, MBA5,2, MBP9,2.
> > 
> > The patch was originally written by adamski99 (ubuntuforums.org) and
> > later tested by janhouse (bbs.archlinux.org).
> > 
> > Signed-off-by: Henrik Rydberg <[email protected]>
> > Signed-off-by: Guenter Roeck <[email protected]>
> > ---
> > 
> > This should apply cleanly at least as far back as 3.0 as-is, and all the
> > way back to 2.6.32 with minor conflicts in the context.
> > 
> > This gets the driver working with newer Macbooks, so it seems worthwhile
> > for stable. I suppose this is arguable though, since the commit message
> > does note a slight (but not noticeable) increase in the fail frequency
> > on older hardware.
> 
> This patch alone is not suitable as a backport, because of the
> negative effects on older hardware. It could however be backported
> together with 829917cd, which seems to improve things on all tested
> machines. Even so, I do think backporting is premature; we should
> probably wait at least until 3.6 is out.

Okay, thanks Henrik. I got the impression from the commit message that
the increased failures on old hardware were insignificant, but sounds
like that isn't the case.

Seth

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