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From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Stephen Boyd <sboyd@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>,
	alexandre.belloni@bootlin.com,
	Michael Turquette <mturquette@baylibre.com>,
	thierry.reding@gmail.com, lee.jones@linaro.org,
	linux-clk@vger.kernel.org, linux-rtc@vger.kernel.org,
	Ludovic.Desroches@microchip.com, o.rempel@pengutronix.de,
	andy.shevchenko@gmail.com, aardelean@deviqon.com,
	linux-pwm@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	broonie@kernel.org, Jonathan.Cameron@huawei.com,
	linux-arm-kernel@lists.infradead.org, a.zummo@towertech.it,
	linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org,
	wsa@kernel.org, kernel@pengutronix.de, akpm@linux-foundation.org,
	torvalds@linux-foundation.org, Claudiu.Beznea@microchip.com
Subject: Re: About clk maintainership [Was: Re: [PULL] Add variants of devm_clk_get for prepared and enabled clocks enabled clocks]
Date: Tue, 3 Aug 2021 12:40:12 +0200	[thread overview]
Message-ID: <20210803104012.wf2buscbukxufesl@pengutronix.de> (raw)
In-Reply-To: <162797831443.714452.3551045763456936564@swboyd.mtv.corp.google.com>

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On Tue, Aug 03, 2021 at 01:11:54AM -0700, Stephen Boyd wrote:
> Quoting Russell King (Oracle) (2021-08-02 09:38:24)
> > On Mon, Aug 02, 2021 at 05:27:55PM +0200, Uwe Kleine-Konig wrote:
> > > Hello Russell,
> > > 
> > > On Mon, Aug 02, 2021 at 10:48:10AM +0100, Russell King (Oracle) wrote:
> > 
> > > > There have been several different approaches to wrapping things up,
> > > > but here's a question: should we make it easier to do the lazy thing
> > > > (get+enable) or should we make it easier to be power efficient?
> > > > Shouldn't we be encouraging people to write power efficient drivers?
> > > 
> > > Yeah, sounds compelling, but I wonder if that's of practical importance.
> > > How many driver authors do you expect to lure into making a better
> > > driver just because devm_clk_get_prepared() doesn't exist? In contrast:
> > > How many drivers become simpler with devm_clk_get_prepared() and so
> > > it becomes easier to maintain them and easier to spot bugs?
> > > In the absence of devm_clk_get_prepared(), is it better that several
> > > frameworks (or drivers) open code it?
> > 
> > It probably depends on where you stand on power management and power
> > efficiency issues. Personally, I would like to see more effort put
> > into drivers to make them more power efficient, and I believe in the
> > coming years, power efficiency is going to become a big issue.
> > 
> 
> I agree we should put more effort into power efficiency in the kernel.
> I've occasionally heard from driver writers that they never will turn
> the clk off even in low power modes though. They feel like it's a
> nuisance to have to do anything with the clk framework in their driver.
> When I say "why not use runtime PM?" I get told that they're not turning
> the clk off because it needs to be on all the time, so using runtime PM
> makes the driver more complicated, not less, and adds no value. I think
> some touchscreens are this way, and watchdogs too. Looking at the
> drivers being converted in this series I suspect RTC is one of those
> sorts of devices as well. But SPI and I2C most likely could benefit from
> using runtime PM and so those ones don't feel appropriate to convert.
> 
> Maybe this series would be more compelling if those various drivers that
> are hand rolling the devm action were converted to the consolidated
> official devm function. The truth is it's already happening in various
> subsystems so consolidating that logic into one place would be a win
> code size wise and very hard to ignore.
> 
> Doing
> 
>  $ git grep devm_add_action | grep clk
> 
> seems to catch quite a few of them.

Another upside is that grepping for these drivers with a potential for
further improvement become easier to grep for as
devm_clk_get_{prepared,enabled} is a much better hint :-)

The changes to these drivers probably won't go through a clk tree, so
adding these patches before adding devm_clk_get_enabled() would only
help for the warm and cozy feeling that it is right to do so, correct?

As my focus is limited to (mostly) drivers/pwm and I already have quite
some other patch quests on my list:

So can I lure you in merging the new functions and I will create a
kernel janitor task to convert more existing drivers?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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  reply	other threads:[~2021-08-03 10:40 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20210510174142.986250-1-u.kleine-koenig@pengutronix.de>
     [not found] ` <20210609202123.u5rmw7al4x3rrvun@pengutronix.de>
     [not found]   ` <20210625171434.3xusxpxjprcdqa47@pengutronix.de>
     [not found]     ` <20210705080144.zfbzkm7l3gmnh6st@pengutronix.de>
     [not found]       ` <20210722060654.nudpdtemosi64nlb@pengutronix.de>
     [not found]         ` <YPkg0wtYIoHKpTUW@kunai>
     [not found]           ` <20210722081817.2tsjzof4gvldq6ka@pengutronix.de>
     [not found]             ` <YPlfcbkxiBmB+vw1@kunai>
     [not found]               ` <CAHp75VfC=s12Unw3+Cn0ag71mM5i90=Jbwj4nYwB5cPKiUTRSA@mail.gmail.com>
2021-07-23  9:13                 ` [PULL] Add variants of devm_clk_get for prepared and enabled clocks enabled clocks Uwe Kleine-König
2021-07-26  9:18                   ` Claudiu.Beznea
2021-07-26  9:52                     ` Andy Shevchenko
2021-07-26 12:32                       ` Wolfram Sang
2021-07-26 13:28                         ` Andy Shevchenko
2021-07-26 17:40                           ` Wolfram Sang
2021-07-28 20:25                     ` About clk maintainership [Was: Re: [PULL] Add variants of devm_clk_get for prepared and enabled clocks enabled clocks] Uwe Kleine-König
2021-07-28 20:40                       ` Russell King (Oracle)
2021-07-31  7:41                         ` Stephen Boyd
2021-07-31  8:07                           ` Andy Shevchenko
2021-07-31 12:00                           ` Uwe Kleine-König
2021-08-02  9:36                             ` Jonathan Cameron
2021-08-02  9:48                             ` Russell King (Oracle)
2021-08-02 15:27                               ` Uwe Kleine-König
2021-08-02 16:38                                 ` Russell King (Oracle)
2021-08-02 17:13                                   ` Andy Shevchenko
2021-08-02 20:28                                     ` Russell King (Oracle)
2021-08-03  8:11                                   ` Stephen Boyd
2021-08-03 10:40                                     ` Uwe Kleine-König [this message]
2021-08-06  0:26                                       ` Stephen Boyd
2021-09-14 13:22                                         ` Uwe Kleine-König
2021-09-14 13:52                                           ` Mark Brown
2021-08-03  7:44                               ` Stephen Boyd

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