From: Ulf Hansson <ulf.hansson@linaro.org>
To: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Arnd Bergmann <arnd@arndb.de>, Kevin Hilman <khilman@kernel.org>,
ssantosh@kernel.org, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Grant Likely <grant.likely@secretlab.ca>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: Re: [PATCH v4 1/2] ARM: keystone: pm: switch to use generic pm domains
Date: Thu, 20 Nov 2014 14:12:41 +0100 [thread overview]
Message-ID: <CAPDyKFrBhZyqozM98_4pPdW0EMFt5W6VX1X7cz6Z=yNhW4vYTA@mail.gmail.com> (raw)
In-Reply-To: <546DD87B.3080806@ti.com>
On 20 November 2014 13:03, Grygorii Strashko <grygorii.strashko@ti.com> wrote:
> On 11/20/2014 01:34 PM, Ulf Hansson wrote:
>> On 19 November 2014 14:47, Arnd Bergmann <arnd@arndb.de> wrote:
>>> On Wednesday 19 November 2014 13:32:45 Grygorii Strashko wrote:
>>>> On 11/18/2014 09:32 PM, Arnd Bergmann wrote:
>>>>> On Tuesday 18 November 2014 20:54:36 Grygorii Strashko wrote:
>>>>>
>>>>> Have one pmdomain driver in the generic code that knows about clocks,
>>>>> possibly also regulators and pins and just turns them on when needed.
>>>>> You can have a "simple-pmdomain" or "generic-pmdomain" compatible
>>>>> string.
>>>>>
>>>>> I'm a bit surprised that your pmdomain code looks up the clocks from the
>>>>> respective device, rather than know about the clocks itself. There is
>>>>> probably a good reason for this, but I don't see it yet.
>>>>
>>>> The keystone 2 uses simple PM schema based on clocks only:
>>>> - clocks enabled -> dev is active
>>>> - clocks disabled -> dev is suspended
>>>>
>>>> To achieve explained above the Generic clock manipulation PM callbacks framework (pm_clk) is used.
>>>> - list of managed clocks is filled for each device (for non-DT case the con_id list
>>>> is specified by platform code like:
>>>> .con_ids = { "fck", "master", "slave", NULL },
>>>> - or -
>>>> .con_ids = { }, <-- in this case only first clock will be added to pm_clk
>>>> )
>>
>> According to earlier comments in this thread, device's clocks are
>> split into "functional" and "PM" clocks.
>>
>> If I understand correctly, a typical platform driver will enable it's
>> "functional" clocks during ->probe() and you want the PM domain to
>> take care of the "PM" clocks, when the device changes runtime PM
>> status.
>>
>> How will you describe these different set of device clocks in DT?
>
> True :( You can dig deeper in the history of this series if you wish.
> - first Geert Uytterhoeven proposed to use CLK_RUNTIME_PM there
> https://lkml.org/lkml/2014/11/6/319
> - second I proposed to introduce smth. like "clkops-clocks", "pm-clocks" there
> https://lkml.org/lkml/2014/6/12/436
> or "fck-clocks"/"opt-clocks" later.
>
> ^failed.
>
> So, this implementation picks up all clocks for each device, which is ok for
> Keystone 2 and, because it's platform specific.
>
>>>
>>> Yes, it would definitely solve the problem that I see with the infrastructure
>>> code that the current version adds into the platform directory.
>>>
>>> The exact binding of course should be reviewed by the pmdomain and
>>> DT maintainers, to ensure that it is done the best possible way, because
>>> I assume we will end up using it a lot, and it would be a shame to get
>>> it slightly wrong.
>>>
>>> One possible variation I can think of would be to just use "simple-pmdomain"
>>> as the compatible string, and use properties in the node itself to decide
>>> what the domain should control, e.g.
>>>
>>> clk_pmdomain: pmdomain {
>>> compatible = "simple-pmdomain";
>>> pmdomain-enable-clocks;
>>> #power-domain-cells = <0>;
>>> };
>>> clk_regulator_pmdomain: pmdomain {
>>> compatible = "simple-pmdomain";
>>> pmdomain-enable-clocks;
>>> pmdomain-enable-regulators;
>>> #power-domain-cells = <0>;
>>> };
>>>
>>> and then have each device link to one of the nodes as the pmdomain.
>>>
>>
>> That's seems like a good approach to me.
>
> Yes, but your previous comment is still actual :(
Agree!
So I really think we need to decide on how to address the split of the
device clocks. Before that's done, I don't think it make sense to add
a "simple-pmdomain" compatible, since it will likely not be that many
SoC that can use it.
So, does anyone have a suggestion on how to deal with the split of the
device clocks into "functional" clocks and into "PM" clocks?
Kind regards
Uffe
next prev parent reply other threads:[~2014-11-20 13:12 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-10 14:59 [PATCH v4 0/2] ARM: keystone: pm: switch to use generic pm domains Grygorii Strashko
2014-11-10 14:59 ` [PATCH v4 1/2] " Grygorii Strashko
2014-11-10 15:06 ` Arnd Bergmann
2014-11-10 17:38 ` Grygorii Strashko
2014-11-10 20:36 ` Arnd Bergmann
2014-11-17 19:14 ` Kevin Hilman
2014-11-17 20:37 ` Arnd Bergmann
2014-11-17 21:50 ` Kevin Hilman
2014-11-18 18:54 ` Grygorii Strashko
2014-11-18 19:32 ` Arnd Bergmann
2014-11-19 11:32 ` Grygorii Strashko
2014-11-19 13:47 ` Arnd Bergmann
2014-11-20 11:34 ` Ulf Hansson
2014-11-20 12:03 ` Grygorii Strashko
2014-11-20 13:12 ` Ulf Hansson [this message]
2014-11-20 13:32 ` Geert Uytterhoeven
2014-11-20 15:32 ` Grygorii Strashko
2014-11-20 20:22 ` Kevin Hilman
2014-11-20 20:26 ` Geert Uytterhoeven
2014-11-20 21:48 ` Kevin Hilman
2014-11-20 21:54 ` Geert Uytterhoeven
2014-11-21 1:30 ` Kevin Hilman
2014-11-21 8:06 ` Geert Uytterhoeven
2014-11-21 18:58 ` Grygorii Strashko
2014-11-21 19:29 ` Kevin Hilman
2014-11-21 20:14 ` Grygorii Strashko
2014-11-24 10:50 ` Arnd Bergmann
2014-11-25 6:44 ` Mike Turquette
2014-11-25 10:33 ` Arnd Bergmann
2014-11-25 11:08 ` Grygorii Strashko
2014-11-25 12:09 ` Arnd Bergmann
2014-11-25 13:30 ` Grygorii Strashko
2014-11-25 14:04 ` Russell King - ARM Linux
2014-11-25 14:53 ` Grygorii Strashko
2014-11-25 16:28 ` santosh shilimkar
2014-11-21 19:20 ` Kevin Hilman
2014-11-21 9:04 ` Geert Uytterhoeven
2014-11-18 2:18 ` santosh.shilimkar
2014-11-10 14:59 ` [PATCH v4 2/2] ARM: dts: keystone: add generic pm controller node Grygorii Strashko
2014-11-10 15:13 ` [PATCH v4 0/2] ARM: keystone: pm: switch to use generic pm domains Grygorii Strashko
2014-11-10 18:51 ` santosh.shilimkar
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