linux-kernel - Re: [PATCHv3 2/8] devfreq: exynos: Add documentation for generic exynos memory bus frequency driver

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Date:	Wed, 21 Jan 2015 15:12:57 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Rob Herring <robherring2@...il.com>,
	MyungJoo Ham <myungjoo.ham@...sung.com>,
	Kukjin Kim <kgene@...nel.org>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	Mark Rutland <mark.rutland@....com>, a.kesavan@...sung.com,
	Tomasz Figa <tomasz.figa@...il.com>,
	Krzysztof Kozłowski <k.kozlowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Rob Herring <robh+dt@...nel.org>,
	InKi Dae <inki.dae@...sung.com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>
Subject: Re: [PATCHv3 2/8] devfreq: exynos: Add documentation for generic
 exynos memory bus frequency driver

On 01/21/2015 01:37 PM, Viresh Kumar wrote:
> On 21 January 2015 at 09:50, Chanwoo Choi <cw00.choi@...sung.com> wrote:
>> If the clock will be stayed on highest voltage, will reduce
>> the considerable benefit of power-consumption.
> 
> But this is exactly what you must be doing right now as well..
> I think I didn't make it clear enough with an example. Let me
> try..
> 
> This is how I feel it should look like:
> 
>        memory_bus_int: memory_bus@1 {
>                // Regulator is shared for all below
>                blocks {
>                        peri_block: memory_bus_block1 {
>                                 operating-points = <
>                                         100000 850000
>                                         50000  850000>;
>                        };
> 
>                        display_block: memory_bus_block2 {
>                                 operating-points = <
>                                         200000 950000
>                                         160000 950000
>                                         100000 925000
>                                         80000  850000
>                                         50000  850000>;
>                        };
> 
>                        isp_block: memory_bus_block3 {
>                                 operating-points = <
>                                         200000 950000
>                                         100000 925000
>                                         80000  850000
>                                         50000  850000>;
>                        };
> 
>                        gps_block: memory_bus_block4 {
>                                 operating-points = <
>                                         300000 950000
>                                         200000 950000
>                                         133000 925000
>                                         100000 850000
>                                         50000  850000>;
>                        };
> 
> 
> Now suppose these are the requirements from all the blocks
> at any point of time:
> - block1: 100000 850000
> - block2: 100000 925000
> - block3: 80000  850000
> - block4: 133000 925000
> 
> Now, all of them can control freq separately and we don't need to
> worry for that. But regulator is shared between them. We can check
> what's the highest voltage requested at this point of time and can
> switch to that.
> 
> i.e. 925000 in this case. And that's not the highest possible one.
> And you will reach to similar conclusion with your current code as
> well I believe.
> 

OK, I understand.
I'll try to update exynos memory bus according to your comment.

Thanks
Chanwoo








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