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From: Bill Huang <bilhuang@nvidia.com>
To: Mike Turquette <mturquette@linaro.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"patches@linaro.org" <patches@linaro.org>,
	"linaro-dev@lists.linaro.org" <linaro-dev@lists.linaro.org>
Subject: Re: [PATCH 2/5] clk: notifier handler for dynamic voltage scaling
Date: Fri, 1 Mar 2013 01:41:31 -0800	[thread overview]
Message-ID: <1362130891.19498.12.camel@bilhuang-vm1> (raw)
In-Reply-To: <1362026969-11457-3-git-send-email-mturquette@linaro.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.



WARNING: multiple messages have this Message-ID (diff)
From: bilhuang@nvidia.com (Bill Huang)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/5] clk: notifier handler for dynamic voltage scaling
Date: Fri, 1 Mar 2013 01:41:31 -0800	[thread overview]
Message-ID: <1362130891.19498.12.camel@bilhuang-vm1> (raw)
In-Reply-To: <1362026969-11457-3-git-send-email-mturquette@linaro.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.

  reply	other threads:[~2013-03-01  9:30 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-28  4:49 [PATCH v3 0/5] common clk framework reentrancy & dvfs, take 3 Mike Turquette
2013-02-28  4:49 ` Mike Turquette
2013-02-28  4:49 ` [PATCH 1/5] clk: allow reentrant calls into the clk framework Mike Turquette
2013-02-28  4:49   ` Mike Turquette
2013-02-28  9:54   ` Ulf Hansson
2013-02-28  9:54     ` Ulf Hansson
2013-03-18 20:15     ` Mike Turquette
2013-03-18 21:00       ` Russell King - ARM Linux
2013-03-18 21:00         ` Russell King - ARM Linux
2013-03-18 21:35         ` Mike Turquette
2013-03-27  3:33   ` Bill Huang
2013-03-27  3:33     ` Bill Huang
2013-03-27  8:38     ` Mike Turquette
2013-02-28  4:49 ` [PATCH 2/5] clk: notifier handler for dynamic voltage scaling Mike Turquette
2013-02-28  4:49   ` Mike Turquette
2013-03-01  9:41   ` Bill Huang [this message]
2013-03-01  9:41     ` Bill Huang
2013-03-01 18:22     ` Mike Turquette
2013-03-01 20:48       ` Mike Turquette
2013-03-02  2:55         ` Bill Huang
2013-03-02  2:55           ` Bill Huang
2013-03-02  8:22           ` Richard Zhao
2013-03-02  8:22             ` Richard Zhao
2013-03-03 10:54             ` Mike Turquette
2013-03-03 10:54               ` Mike Turquette
2013-03-03 13:27               ` Richard Zhao
2013-03-03 13:27                 ` Richard Zhao
2013-03-04  7:25                 ` Mike Turquette
2013-03-13 13:59                   ` Ulf Hansson
2013-03-13 13:59                     ` Ulf Hansson
2013-03-01 20:49     ` Stephen Warren
2013-03-01 20:49       ` Stephen Warren
2013-03-02  2:58       ` Bill Huang
2013-03-02  2:58         ` Bill Huang
2013-03-10 10:21   ` Francesco Lavra
2013-03-10 10:21     ` Francesco Lavra
2013-04-02 17:49   ` Taras Kondratiuk
2013-04-02 17:49     ` Taras Kondratiuk
2013-02-28  4:49 ` [PATCH 3/5] cpufreq: omap: scale regulator from clk notifier Mike Turquette
2013-02-28  4:49   ` Mike Turquette
2013-02-28  4:49 ` [PATCH 4/5] HACK: set_parent callback for OMAP4 non-core DPLLs Mike Turquette
2013-02-28  4:49   ` Mike Turquette
2013-02-28  4:49 ` [PATCH 5/5] HACK: omap: opp: add fake 400MHz OPP to bypass MPU Mike Turquette
2013-02-28  4:49   ` Mike Turquette

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