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In-Reply-To: <1283396674-4865-1-git-send-email-ccross@android.com>
References: <1283396674-4865-1-git-send-email-ccross@android.com>
Date: Fri, 12 Nov 2010 13:39:50 +0100
Message-ID: <AANLkTinsRCinLdhq1xj0tx09Jb=Tohdbd7PUD=ae1q3m@mail.gmail.com>
Subject: Re: [PATCH] [ARM] twd: Allow twd rescaling to match cpu frequency
From: Linus Walleij <linus.ml.walleij@gmail.com>
To: Colin Cross <ccross@android.com>
Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Russell King <linux@arm.linux.org.uk>,
        srinidhi kasagar <srinidhi.kasagar@stericsson.com>,
        Varun Swara <Varun.Swara@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Harald.Gustafsson@ericsson.com,
        Rickard ANDERSSON <Rickard.Andersson@stericsson.com>
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Hi Colin,

2010/9/2 Colin Cross <ccross@android.com>:

> The clock to the ARM TWD local timer scales with the cpu
> frequency. ?To allow the cpu frequency to change while
> maintaining a constant TWD frequency, pick a lower target
> frequency for the TWD and use the prescaler to divide down
> to the closest lower frequency.
>
> This patch provides a new initialization function that takes
> a target TWD frequency and the relation between the cpu
> clock and the TWD clock, required to be an integer divider
>>= 2 by the ARM spec. ?It also provides a function to be
> called from cpufreq drivers to set the prescaler whenever
> the cpu frequency changes.

What's the status of this patch?

We have basically the same problem so we'd really like
a generic solution to this problem.

Our only comment is that we cannot see the reason for
not using the CPUfreq notifiers as most scaling code
is, but I assume there is some specific reason for this?

Unless something holds this back, could you post it to
Russells patch tracker, we might have an add-on patch
for the U8500 later.

Yours,
Linus Walleij
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