From mboxrd@z Thu Jan  1 00:00:00 1970
From: bilhuang@nvidia.com (Bill Huang)
Date: Fri, 1 Mar 2013 01:41:31 -0800
Subject: [PATCH 2/5] clk: notifier handler for dynamic voltage scaling
In-Reply-To: <1362026969-11457-3-git-send-email-mturquette@linaro.org>
References: <1362026969-11457-1-git-send-email-mturquette@linaro.org>
 <1362026969-11457-3-git-send-email-mturquette@linaro.org>
Message-ID: <1362130891.19498.12.camel@bilhuang-vm1>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Thu, 2013-02-28 at 12:49 +0800, Mike Turquette wrote:
> Dynamic voltage and frequency scaling (dvfs) is a common power saving
> technique in many of today's modern processors.  This patch introduces a
> common clk rate-change notifier handler which scales voltage
> appropriately whenever clk_set_rate is called on an affected clock.

I really think clk_enable and clk_disable should also be triggering
notifier call and DVFS should act accordingly since there are cases
drivers won't set clock rate but instead disable its clock directly, do
you agree?
> 
> There are three prerequisites to using this feature:
> 
> 1) the affected clocks must be using the common clk framework
> 2) voltage must be scaled using the regulator framework
> 3) clock frequency and regulator voltage values must be paired via the
> OPP library

Just a note, Tegra Core won't meet prerequisite #3 since each regulator
voltage values is associated with clocks driving those many sub-HW
blocks in it.