linux-kernel - Re: [PATCH v2 0/5] Cpufreq frequency serialization fixes

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Date:	Mon, 28 Apr 2014 23:57:34 +0300 (EEST)
From:	Meelis Roos <mroos@...ux.ee>
To:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
cc:	rjw@...ysocki.net, viresh.kumar@...aro.org,
	cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/5] Cpufreq frequency serialization fixes

> Meelis Roos reported hangs during boot in the longhaul cpufreq driver, after
> commit 12478cf0c55 (cpufreq: Make sure frequency transitions are serialized).
> The root-cause of this issue is the extra invocation of the
> cpufreq_freq_transition_begin() and cpufreq_freq_transition_end() APIs in the
> longhaul driver. I found similar issues in the powernow-k6 and powernow-k7
> drivers as well. This patchset fixes the issue in all the 3 drivers and also
> adds a debug infrastructure to catch such issues easily.
> 
> Patches 1-4 fix the regression in longhaul, powernow-k6 and powernow-k7
> drivers. (Patch 2 fixes a different bug in powernow-k6, and it is kept as a
> separate patch instead of merging it with patch 3, because I felt that it was
> a bit subtle and needed attention in a separate patch).
> 
> Patch 5 adds a debug infrastructure to the cpufreq core to catch such problems
> more easily in the future.
> 
> 
> Changes in v2:
> --------------
> 
> * Modified patch 1 to take error returns into account, as pointed out by
>   Viresh.
> * Added patch 2 to fix the existing issue in the powernow-k6 driver, pointed
>   out by Viresh.
> * Added patch 5 to introduce a debug infrastructure to catch such issues
>   easily.

This also works on my VIA EPIA.

-- 
Meelis Roos (mroos@...ux.ee)
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