Messages in this thread | | | From | Harald Gustafsson <> | Date | Fri, 12 Nov 2010 13:49:50 +0100 | Subject | RE: [PATCH] [ARM] twd: Allow twd rescaling to match cpu frequency |
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Hi,
Don't forget the other patches to make this work:
[ARM] twd: Always calibrate local timer [ARM] twd: Fix updating control register in set_mode [ARM] twd: Fix prescaler getting cleared by set_mode
/Harald Gustafsson ________________________________________ From: Linus Walleij [linus.ml.walleij@gmail.com] Sent: Friday, November 12, 2010 1:39 PM To: Colin Cross Cc: linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org; Russell King; srinidhi kasagar; Varun Swara; Catalin Marinas; Harald Gustafsson; Rickard ANDERSSON Subject: Re: [PATCH] [ARM] twd: Allow twd rescaling to match cpu frequency
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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