Message-ID: <1454366.cVgT9MeyeC@diego>
Date:	Fri, 28 Nov 2014 10:57 +0100
From:	Heiko Stübner <heiko@...ech.de>
To:	Caesar Wang <caesar.wang@...k-chips.com>, khilman@...nel.org,
	tfiga@...omium.org
Cc:	linus.walleij@...aro.org, linux-arm-kernel@...ts.infradead.org,
	Russell King <linux@....linux.org.uk>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Grant Likely <grant.likely@...aro.org>,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	Randy Dunlap <rdunlap@...radead.org>,
	linux-doc@...r.kernel.org, dianders@...omium.org,
	linux-rockchip@...ts.infradead.org,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	fzf@...k-chips.com, cf@...k-chips.com, chris.zhong@...k-chips.com,
	xxm@...k-chips.com, chm@...k-chips.com, djkurtz@...omium.org,
	"jinkun.hong" <jinkun.hong@...k-chips.com>,
	Jack Dai <jack.dai@...k-chips.com>
Subject: Re: [PATCH v12 0/3] ARM: rk3288: Add PM Domain support

Am Montag, 17. November 2014, 17:50:38 schrieb Caesar Wang:
>     Add power domain drivers based on generic power domain for
>     Rockchip platform, and support RK3288.
> 
>     https://chromium-review.googlesource.com/#/c/220253/9
>     This is the GPU driver, add the following information in DT,
>     and it can support the PMDOMAIN

I'm not sure what to do with this series. Kevin had concerns about the clocks 
being part of the power-domains and I don't see them actually addressed and/or 
Kevin being satisfied - actually he isn't even on the recipients list of this 
version of the series.


@Ceasar: you should include people being part of important previous 
conversations in new versions of patchsets - especially when they have voiced 
concerns.


I've added Tomasz whom I remember having previous experience on the Exynos 
Powerdomains, so maybe he can add some other perspective - new ideas.


@Tomasz: this is the part of Kevin's concerns from v10 of the powerdomain 
series:

Am Donnerstag, 13. November 2014, 12:24:47 schrieben Kevin Hilman:
> Heiko Stübner <heiko@...ech.de> writes:
> > Am Dienstag, 11. November 2014, 08:53:13 schrieb Kevin Hilman:
> >> I still don't like having lists of clocks in the power-domain DT.
> >> 
> >> DT is supposed to describe the hardware, and clocks are properties of
> >> devices, not power-domains, so the DT description should follow from
> >> that.
> > 
> > on the policy side one could argue that if the clock needs to be enabled
> > to
> > achieve sucessful domain state-changes, that it is also a property of the
> > domain itself in addition to the device.
> 
> You could, but from a hardware perspective, the clock is a property of
> the device.
> 
> > And on the pratical side we don't have drivers nor bindings for a big part
> > of the domain users - and this will probably be true for quite some time.
> > This of course makes it very impractical (or impossible) to collect the
> > clocks for parts like the gpu (mali), hevc, vcodec (video
> > encoder/decoder), rga (2d stuff), iep, isp.
> 
> This doesn't sound impossible at all.
> 
> You have to collect the clocks anyways.  The only debate is whether to
> list them in the device node or the power-domain node.
> 
> Even for devices without drivers, you just need a minimal node in the DT if
> which lists the clocks and has a phandle to the parent power domain.
> 
> Sounds rather simple to me, and since the DT is supposed to describe the
> hardware, doing it this way makes looking at the DT actually help
> understand the hardware.

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