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Message-ID: <4BD25E1A.50505@codeaurora.org>
Date: Fri, 23 Apr 2010 19:57:30 -0700
From: Saravana Kannan <skannan@codeaurora.org>
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Subject: Re: CPUfreq - udelay() interaction issues
References: <4BCFC3D0.5080904@codeaurora.org>	<4BD0D9E5.3020606@codeaurora.org>	<20100423184042.GA16190@Krystal> <20100423122259.49e0416a@infradead.org>
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To: Arjan van de Ven <arjan@infradead.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, cpufreq <cpufreq@vger.kernel.org>, linux-arm-msm <linux-arm-msm@vger.kernel.org>, Dave Jones <davej@redhat.com>, Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>, Thomas Renninger <trenn@suse.de>, linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>, Peter Zijlstra <peterz@infradead.org>

Arjan van de Ven wrote:
> so in reality, all hardware that does coordination between cores/etc
> like this also has a tsc that is invariant of the actual P state.
> If there are exceptions, those have a problem, but I can't think of any
> right now.
> Once the TSC is invariant of P state, udelay() is fine, since that goes
> of the tsc, not of some delay loop kind of thing....

I assume you are talking specifically about x86. I want x86 to be 
correct, but also want ARM to be correct. So, at this point I might as 
well try to put in an arch independent fix.

Thanks,
Saravana