linux-kernel - Re: [PATCH V4 3/3] cpufreq: Tegra: implement intermediate frequency callbacks

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Date:	Mon, 02 Jun 2014 10:50:20 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
CC:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Arvind Chauhan <arvind.chauhan@....com>,
	Stephen Warren <swarren@...dia.com>,
	Doug Anderson <dianders@...omium.org>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Thomas Abraham <thomas.abraham@...aro.org>,
	Peter De Schrijver <pdeschrijver@...dia.com>
Subject: Re: [PATCH V4 3/3] cpufreq: Tegra: implement intermediate frequency
 callbacks

On 06/02/2014 04:06 AM, Viresh Kumar wrote:
> On 30 May 2014 21:56, Stephen Warren <swarren@...dotorg.org> wrote:
>> ... [This patch causes issues on Tegra20] ...
>> I believe the issue is this:
...
> Okay, that was very helpful..
> 
> What about this ? (Attached for testing) :
> 
> Author: Viresh Kumar <viresh.kumar@...aro.org>
> Date:   Fri May 16 14:22:40 2014 +0530
> 
>     cpufreq: Tegra: implement intermediate frequency callbacks
> 
>     Tegra had always been switching to intermediate frequency (pll_p_clk) since
>     ever. CPUFreq core has better support for handling notifications for these
>     frequencies and so we can adapt Tegra's driver to it.
> 
>     Also do a WARN() if clk_set_parent() fails while moving back to pll_x as we
>     should have atleast restored to earlier frequency on error.

Tested-by: Stephen Warren <swarren@...dia.com>

I'd prefer a couple of changes though:

a) Rename "pll_p_clk_count" to better describe what it represents. It
represents the fact that pll_x has been prepare_enabled, so why not call
it "pll_x_prepared"?

b) I think it should be a Boolean not an integer; there should never be
a case where the value is not 0 or 1. The only way that could happen is
if the cpufreq core called tegra_target_intermediate() out of sequence
too many times.

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