linux-kernel - Re: [PATCH v14 0/3] ARM: rk3288: Add PM Domain support

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Message-ID: <7h383lzaqt.fsf@deeprootsystems.com>
Date:	Mon, 27 Apr 2015 11:28:42 -0700
From:	Kevin Hilman <khilman@...nel.org>
To:	Heiko Stübner <heiko@...ech.de>
Cc:	Caesar Wang <wxt@...k-chips.com>, tomasz.figa@...il.com,
	linux-arm-kernel@...ts.infradead.org, linus.walleij@...aro.org,
	robh+dt@...nel.org, pawel.moll@....com, mark.rutland@....com,
	galak@...eaurora.org, grant.likely@...aro.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	rdunlap@...radead.org, linux-doc@...r.kernel.org,
	dianders@...omium.org, linux-rockchip@...ts.infradead.org,
	ulf.hansson@...aro.org, dmitry.torokhov@...il.com,
	broonie@...nel.org, ijc+devicetree@...lion.org.uk,
	linux@....linux.org.uk
Subject: Re: [PATCH v14 0/3] ARM: rk3288: Add PM Domain support

Heiko Stübner <heiko@...ech.de> writes:

> Am Freitag, 24. April 2015, 16:07:45 schrieb Caesar Wang:
>>     Add power domain drivers based on generic power domain for
>> Rockchip platform, and support RK3288.
>> 
>>     Verified on url =
>>     https://chromium.googlesource.com/chromiumos/third_party/kernel.
>> 
>>     At the moment,there are mass of products are using the driver.
>> I believe the driver can happy work for next kernel.
>
> I've taken a look at the driver and here are some global remarks:
>
> (1) You provide dt-bindings/power-domain/rk3288.h in patch 3. This breaks
> bisectability, as the driver itself in patch 2 also includes the header and
> would thus fail to compile if the later patch 3 is missing.
> Ideally I think the header addition should be a separate patch itself, so that
> we can possibly share it between driver and dts branches.
> So 1: binding doc, 2: binding-header, 3: driver, 4: dts-changes.
>
>
> (2) The dts-changes in patch 3 should also add any necessary power-domain
> assignment on devices if they're still missing, so that we don't introduce
> regressions. In my case my work-in-progress edp died because the powerdomain
> was turned off automatically it seems.
>
>
> (3) more like wondering @Kevin or so, is there some more generic place for a
> power-domain driver nowadays?

I think the preference has been to put these under drivers/soc/<vendor> for now,
so they can shared across arm32 and arm64.

> (4) As Tomasz remarked previously the dts should represent the hardware and
> the power-domains are part of the pmu. There is a recent addition from Linus
> Walleij, called simple-mfd [a] that is supposed to get added real early for
> kernel 4.2. So I'd think the power-domains should use that and the patchset
> modified to include the changes shown below [b]?
>
> (5) Keven Hilman and Tomasz had reservations about all the device clocks
> being listed in the power-domains itself in the previous versions. I don't see
> a comment from them yet changing that view.

Correct.  

> Their wish was to get the clocks by reading the clocks from the device nodes,
> though I see a problem on how to handle devices that do not have any bindings
> at all yet.
>
> Kevin, Tomasz any new thoughts?

I don't see any issues with devices that don't have bindings, as all
that would be needed would be to simple device nodes with a clock
property.  I wouldn't even matter if those devices had device drivers.

Kevin
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