linux-kernel - Re: [PATCH 00/27] add pm_runtime_last_busy_and

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Date:	Thu, 25 Sep 2014 21:54:36 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Wolfram Sang <wsa@...-dreams.de>, Vinod Koul <vinod.koul@...el.com>
Cc:	Felipe Balbi <balbi@...com>, linux-kernel@...r.kernel.org,
	subhransu.s.prusty@...el.com,
	Alan Stern <stern@...land.harvard.edu>,
	Alexandre Courbot <acourbot@...dia.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Gross <agross@...eaurora.org>,
	Baruch Siach <baruch@...s.co.il>,
	Ben Skeggs <bskeggs@...hat.com>,
	Bjorn Andersson <bjorn.andersson@...ymobile.com>,
	"Chew, Chiau Ee" <chiau.ee.chew@...el.com>,
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	Dan Carpenter <dan.carpenter@...cle.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Dave Airlie <airlied@...hat.com>,
	David Herrmann <dh.herrmann@...il.com>,
	dmaengine@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	"Du, Wenkai" <wenkai.du@...el.com>,
	Grant Grundler <grundler@...omium.org>,
	Ilia Mirkin <imirkin@...m.mit.edu>,
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	"Ivan T. Ivanov" <iivanov@...sol.com>,
	Jaehoon Chung <jh80.chung@...sung.com>,
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	Jingoo Han <jg1.han@...sung.com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
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	linux-arm-kernel@...ts.infradead.org, linux-doc@...r.kernel.org,
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	linux-mmc@...r.kernel.org, linux-nfc@...1.01.org,
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	linux-serial@...r.kernel.org, linux-spi@...r.kernel.org,
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	Marcin Wojtas <mw@...ihalf.com>,
	Mika Westerberg <mika.westerberg@...ux.jf.intel.com>,
	patches@...nsource.wolfsonmicro.com,
	Pramod Gurav <pramod.gurav@...rtplayin.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Rob Clark <robdclark@...il.com>,
	Romain Baeriswyl <Romain.Baeriswyl@...lis.com>,
	Russell King <rmk+kernel@....linux.org.uk>,
	Seungwon Jeon <tgih.jun@...sung.com>,
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	Thierry Reding <treding@...dia.com>,
	Tim Kryger <tim.kryger@...aro.org>,
	Tomi Valkeinen <tomi.valkeinen@...com>,
	Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH 00/27] add pm_runtime_last_busy_and_autosuspend() helper

On Thursday, September 25, 2014 04:27:58 PM Wolfram Sang wrote:
> 
> --Bn2rw/3z4jIqBvZU
> Content-Type: text/plain; charset=us-ascii
> Content-Disposition: inline
> Content-Transfer-Encoding: quoted-printable
> 
> On Thu, Sep 25, 2014 at 09:22:01AM -0500, Felipe Balbi wrote:
> > On Thu, Sep 25, 2014 at 01:27:18PM +0530, Vinod Koul wrote:
> > > On Wed, Sep 24, 2014 at 03:32:19PM -0500, Felipe Balbi wrote:
> > > > > > > OK, I guess this is as good as it gets.
> > > > > > >=20
> > > > > > > What tree would you like it go through?
> > > > > >=20
> > > > > > Do we really need this new helper ? I mean, the very moment when =
> we
> > > > > > decide to implement ->runtime_idle() we will need to get rid of t=
> his
> > > > > > change. I wonder if it's really valid...
> > > > >=20
> > > > > I'm not sure I'm following?  This seems to simply implement what dr=
> ivers
> > > > > have been doing already as one function.  Why would it be invalid t=
> o reduce
> > > > > code duplication?
> > > >=20
> > > > For two reasons:
> > > >=20
> > > > 1) the helper has no inteligence whatsoever. It just calls the same
> > > > functions.
> > > >=20
> > > > 2) the duplication will vanish whenever someone implements
> > > > ->runtime_idle() and have that call pm_runtime_autosuspend() (like PCI
> > > > and USB buses are doing today). This will just be yet another line th=
> at
> > > > needs to change.
> > > >=20
> > > > Frankly though, no strong feelings, I just think it's a commit that
> > > > doesn't bring that any benefits other than looking like one line was
> > > > removed.
> > > and yes that is what it tries to do nothing more nothing less. If in fu=
> ture
> > > there are no users (today we have quite a few), then we can remove the =
> dead
> > > macro, no harm. But that is not the situation today.
> >=20
> > as I said, a commit that's bound to be useless. It's not like you're
> > saving 10 lines of code, it's only one. Replacing two simple lines with
> > a function which takes <joke> almost as many characters to type </joke>.
> >=20
> > IMO, this is pretty useless and I'd rather not see them in the drivers I
> > maintain, sorry.
> 
> It is not a NACK from me; yet from a high-level perspective I agree with
> Felipe.

OK

I'd rather not merge something that driver people don't want to use.

Vinod?

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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