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From: Stephen Boyd <sboyd@codeaurora.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Lists linaro-kernel <linaro-kernel@lists.linaro.org>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	Arvind Chauhan <arvind.chauhan@arm.com>,
	linux-arm-msm@vger.kernel.org, Sachin Kamat <spk.linux@gmail.com>,
	Thomas P Abraham <thomas.ab@samsung.com>,
	Shawn Guo <shawn.guo@linaro.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Nishanth Menon <nm@ti.com>, Tomasz Figa <t.figa@samsung.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Kukjin Kim <kgene.kim@samsung.com>,
	Michal Simek <michal.simek@xilinx.com>,
	Mike Turquette <mturquette@linaro.org>,
	Rob Herring <rob.herring@linaro.org>,
	Santosh Shilimkar <santosh.shilimkar@ti.com>,
	Simon Horman <horms@verge.net.au>
Subject: Re: [PATCH 00/14] cpufreq: cpu0: Extend support beyond CPU0, V2
Date: Wed, 02 Jul 2014 18:24:03 -0700	[thread overview]
Message-ID: <53B4B0B3.9080000@codeaurora.org> (raw)
In-Reply-To: <CAKohpomRttWnCBGEpR3cVsGYniJSnjWUnvtbg21AiYyrUnDjGw@mail.gmail.com>

On 07/01/14 21:12, Viresh Kumar wrote:
> On 1 July 2014 22:02, Viresh Kumar <viresh.kumar@linaro.org> wrote:
>> V1: https://lkml.org/lkml/2014/6/25/152
>>
>> Stephen Boyd sent few patches some time back around a new cpufreq driver for
>> Qualcomm's Krait SoC: https://lkml.org/lkml/2014/6/24/918.
>>
>> Krait couldn't use existing cpufreq-cpu0 driver as it doesn't have support for
>> SoC's with multiple clusters or SoC's which don't share clock line across all
>> CPUs.
>>
>> This patchset is all about extending support beyond CPU0. It can be used for
>> platforms like Krait or ARM big LITTLE architecture now.
>>
>> First two patches add helper routine for of and clk layer, which would be used
>> by later patches.
>>
>> Third one adds space for driver specific data in 'struct cpufreq_policy' and
>> later ones migrate cpufreq-cpu0 to cpufreq-generic, i.e. can be used for SoCs
>> which don't share clock lines across all CPUs.
>>
>> @Stephen: I haven't added your Tested-by as there were few modifications since
>> the time you tested it last.
>>
>> Pushed here:
>> Rebased over v3.16-rc3:
>> git://git.linaro.org/people/viresh.kumar/linux.git cpufreq/cpu0-krait-v2
> Hi Stephen,
>
> As suggested by you I have updated patch
>
> 7/14: cpufreq: cpu0: OPPs can be populated at runtime
> 12/14: cpufreq: cpu0: Extend support beyond CPU0
>
> and dropped
> 2/14: clk: Create of_clk_shared_by_cpus()
>
> Please see if they look fine and work for you.
>
> git://git.linaro.org/people/viresh.kumar/linux.git cpufreq/cpu0-krait-v3

I gave it a spin. It works so you can have my

Tested-by: Stephen Boyd <sboyd@codeaurora.org>

I'm still concerned about the patch where we figure out if the clocks
are shared. I worry about a configuration where there are different
clocks for on/off (i.e. gates) that are per-cpu but they all source from
the same divider or something that is per-cluster. In DT this may be
described as different clock provider outputs for the gates and in the
cpu node we would have different clock specifiers but in reality all the
CPUs in that cluster are affected by the same frequency scaling.

In this case we'll need to get help from the clock framework to
determine that those gates clocks don't have any .set_rate() callback so
they can't actually change rate independently, and then walk up the tree
to their parents to see if they have a common ancestor that does change
rates. That's where it becomes useful to have a clock framework API for
this, like clk_shares_rate(struct clk *clk, struct clk *peer) or
something that can hide all this from cpufreq. Here's what I think it
would look like (totally untested/uncompiled):

static struct clk *find_rate_changer(struct clk *clk)
{	

	if (!clk)
		return NULL; 

	do {
		/* Rate could change by changing parents */
		if (clk->num_parents > 1)
			return clk;

		/* Rate could change by calling clk_set_rate() */
		if (clk->ops->set_rate)
			return clk;

		/* 
		 * This is odd, clk_set_rate() doesn't propagate 
		 * and this clock can't change rate or parents
		 * so we must be at the root and the clock we
		 * started at can't change rates. Just return the
		 * root so that we can see if the other clock shares
		 * the same root although CPUfreq should never care.
		 */
		if (!(clk->flags & CLK_SET_RATE_PARENT))
			return clk;
	} while ((clk = clk->parent))

	return NULL;
}

bool clk_shares_rate(struct clk *clk, struct clk *peer)
{
	struct clk *p1, *p2;

	p1 = find_rate_changer(clk);
	p2 = find_rate_changer(peer)

	return p1 == p2;
}


-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation


  reply	other threads:[~2014-07-03  1:24 UTC|newest]

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-01 16:32 Viresh Kumar
2014-07-01 16:32 ` [PATCH 01/14] of: Create of_property_match() Viresh Kumar
2014-07-01 16:32 ` [PATCH 02/14] clk: Create of_clk_shared_by_cpus() Viresh Kumar
2014-07-01 18:00   ` Stephen Boyd
2014-07-02  1:57     ` Viresh Kumar
2014-07-09 14:38   ` Santosh Shilimkar
2014-07-09 14:38     ` Santosh Shilimkar
2014-07-09 15:20     ` Viresh Kumar
     [not found]   ` <5f7164d789e87c62d722b575980c92dfd0504334.1404231535.git.viresh.kumar@linar o.org>
2014-07-28 14:01     ` Grant Likely
2014-07-28 14:01       ` Grant Likely
2014-07-01 16:32 ` [PATCH 03/14] cpufreq: Add support for per-policy driver data Viresh Kumar
2014-07-09 14:33   ` Santosh Shilimkar
2014-07-09 14:33     ` Santosh Shilimkar
2014-07-09 15:07     ` Viresh Kumar
2014-07-01 16:32 ` [PATCH 04/14] cpufreq: cpu0: Add Module Author Viresh Kumar
2014-07-09 14:42   ` Santosh Shilimkar
2014-07-09 14:42     ` Santosh Shilimkar
2014-07-09 15:08     ` Viresh Kumar
2014-07-09 15:24       ` Santosh Shilimkar
2014-07-01 16:32 ` [PATCH 05/14] cpufreq: cpu0: don't validate clock on clk_put() Viresh Kumar
2014-07-09 14:42   ` Santosh Shilimkar
2014-07-09 14:42     ` Santosh Shilimkar
2014-07-01 16:32 ` [PATCH 06/14] cpufreq: cpu0: defer probe if clock isn't registered yet Viresh Kumar
2014-07-02  5:53   ` Shawn Guo
2014-07-02  5:53     ` Shawn Guo
2014-07-02  5:55     ` Viresh Kumar
2014-07-02 11:32       ` Viresh Kumar
2014-07-03  0:38         ` Stephen Boyd
2014-07-03  2:19           ` Viresh Kumar
2014-07-09 14:43             ` Santosh Shilimkar
2014-07-09 14:43               ` Santosh Shilimkar
2014-07-01 16:32 ` [PATCH 07/14] cpufreq: cpu0: OPPs can be populated at runtime Viresh Kumar
2014-07-01 18:02   ` Stephen Boyd
2014-07-02  2:03     ` Viresh Kumar
2014-07-02  4:03   ` [PATCH V2 Resend " Viresh Kumar
2014-07-09 14:44   ` [PATCH " Santosh Shilimkar
2014-07-09 14:44     ` Santosh Shilimkar
2014-07-09 15:09     ` Viresh Kumar
2014-07-10 11:19     ` Viresh Kumar
2014-07-10 12:39       ` Nishanth Menon
2014-07-10 13:31         ` Santosh Shilimkar
2014-07-10 13:36           ` Viresh Kumar
2014-07-01 16:32 ` [PATCH 08/14] cpufreq: cpu0: use dev_{err|warn|dbg} instead of pr_{err|warn|debug} Viresh Kumar
2014-07-09 14:45   ` Santosh Shilimkar
2014-07-09 14:45     ` Santosh Shilimkar
2014-07-01 16:32 ` [PATCH 09/14] cpufreq: cpu0: Move per-cluster initialization code to ->init() Viresh Kumar
2014-07-03  0:43   ` Stephen Boyd
2014-07-03  2:11     ` Viresh Kumar
2014-07-09 14:53   ` Santosh Shilimkar
2014-07-09 14:53     ` Santosh Shilimkar
2014-07-09 15:17     ` Viresh Kumar
2014-07-09 15:26       ` Santosh Shilimkar
2014-07-09 15:27         ` Viresh Kumar
2014-07-09 15:29           ` Santosh Shilimkar
2014-07-09 15:33             ` Viresh Kumar
2014-07-01 16:32 ` [PATCH 10/14] cpufreq: cpu0: try regulators with name "cpu-supply" Viresh Kumar
2014-07-01 16:32 ` [PATCH 11/14] cpufreq: cpu0: Make allocate_resources() work for any CPU Viresh Kumar
2014-07-01 16:32 ` [PATCH 12/14] cpufreq: cpu0: Extend support beyond CPU0 Viresh Kumar
2014-07-02  4:03   ` [PATCH V2 Resend " Viresh Kumar
2014-07-01 16:32 ` [PATCH 13/14] cpufreq: cpu0: rename driver and internals to 'cpufreq_generic' Viresh Kumar
2014-07-01 16:32 ` [PATCH 14/14] cpufreq: generic: set platform_{driver|device} '.name' to 'cpufreq-generic' Viresh Kumar
2014-07-02  4:12 ` [PATCH 00/14] cpufreq: cpu0: Extend support beyond CPU0, V2 Viresh Kumar
2014-07-03  1:24   ` Stephen Boyd [this message]
2014-07-03  2:44     ` Viresh Kumar
2014-07-03 22:16       ` Mike Turquette
2014-07-04  4:21         ` Viresh Kumar
2014-07-08  4:50           ` Viresh Kumar
2014-07-09 17:41             ` Stephen Boyd
2014-07-16 16:01             ` Viresh Kumar
2014-07-16 17:28               ` Thomas Petazzoni
2014-07-16 21:17                 ` Rafael J. Wysocki
2014-07-16 21:18               ` Rafael J. Wysocki
2014-07-17  0:28                 ` Viresh Kumar
2014-07-17  7:35                   ` Thomas Petazzoni
2014-07-17  7:41                     ` Viresh Kumar
2014-07-18  1:02                       ` Rafael J. Wysocki
2014-07-18  4:17                         ` Viresh Kumar
     [not found]                           ` <CAKohpomKzK8pMJs1gv+uXxhd17HtCQyfjSnVYw9KpGz6FwbgDA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-07-24 10:48                             ` Viresh Kumar
2014-07-24 10:48                               ` Viresh Kumar
2014-07-25 14:29                               ` Rob Herring
     [not found]                                 ` <CAL_JsqKqCeU0zs+rS1vxsOeh=Kuw_-gaVHtGU76Lb6TchCTytw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-07-25 14:34                                   ` Viresh Kumar
2014-07-25 14:34                                     ` Viresh Kumar
2014-07-25 15:41                                 ` Thomas Petazzoni

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