Re: applesmc oops in 3.10/3.11

[Guenter Roeck]

On Wed, Oct 09, 2013 at 10:29:39AM +0200, Henrik Rydberg wrote:
> From 18fa0f55b764ad0fe5fc49f81bae281e5110ed56 Mon Sep 17 00:00:00 2001
> From: Henrik Rydberg <rydberg@xxxxxxxxxxx>
> Date: Wed, 2 Oct 2013 19:15:03 +0200
> Subject: [PATCH] hwmon: (applesmc) Always read until end of data
> 
> The crash reported and investigated in commit 5f4513 turned out to be
> caused by a change to the read interface on newer (2012) SMCs.
> 
> Tests by Chris show that simply reading the data valid line is enough
> for the problem to go away. Additional tests show that the newer SMCs
> no longer wait for the number of requested bytes, but start sending
> data right away.  Apparently the number of bytes to read is no longer
> specified as before, but instead found out by reading until end of
> data. Failure to read until end of data confuses the state machine,
> which eventually causes the crash.
> 
> As a remedy, assuming bit0 is the read valid line, make sure there is
> nothing more to read before leaving the read function.
> 
> Tested to resolve the original problem, and runtested on MBA3,1,
> MBP4,1, MBP8,2, MBP10,1, MBP10,2. The patch seems to have no effect on
> machines before 2012.
> 
> Tested-by: Chris Murphy <chris@xxxxxxxxx>
> Signed-off-by: Henrik Rydberg <rydberg@xxxxxxxxxxx>

Applied. I'll do my usual sanity testing and send it to Linus
either tomorrow or Friday.

Thanks,
Guenter
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