linux-kernel - Re: [PATCH] ARM: twd: Adjust localtimer frequency with cpufreqnotifiers

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Message-ID: <AANLkTi=KcmqmghVxhwGvv79heRU3C+TC-v2VnWSWt7bU@mail.gmail.com>
Date:	Sun, 6 Mar 2011 13:06:36 +0100
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Santosh Shilimkar <santosh.shilimkar@...com>
Cc:	Colin Cross <ccross@...roid.com>,
	Rob Herring <robherring2@...il.com>,
	Russell King <linux@....linux.org.uk>,
	Srinidhi KASAGAR <srinidhi.kasagar@...ricsson.com>,
	Harald Gustafsson <harald.gustafsson@...csson.com>,
	Linus Walleij <linus.ml.walleij@...il.com>,
	linux-kernel@...r.kernel.org,
	Rickard ANDERSSON <rickard.andersson@...ricsson.com>,
	Varun Swara <Varun.Swara@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	martin persson <martin.persson@...ricsson.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] ARM: twd: Adjust localtimer frequency with cpufreqnotifiers

On Sat, Mar 5, 2011 at 9:19 AM, Santosh Shilimkar
<santosh.shilimkar@...com> wrote:

> While doing this patch for OMAP I also found that
> CPUFREQ notifiers does delays scaling timer frequency
> and there is a tick deviation(3-4 ms) around 1st tick and
> last tick around twd rescaling.

Is this caused by ticks that have been programmed
already (based on the previous frequency) when the scaling
takes effect? (That's most likely I think.)

The latter could be fixed by simply calling
schedule() for each CPU connected in the same core as
the TWD at the end of twd_update_cpu_frequency(),
couldn't it?

Colin what do you say?

> Another issue was not able to select higher fixed twd rate
> and found fix for the same.

Can you send out the patch?

Yours,
Linus Walleij
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