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Date: Sat, 28 Jan 2017 11:22:07 -0800
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@codeaurora.org>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Andy Shevchenko <andy.shevchenko@gmail.com>, linux-clk@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] clk: add more managed APIs
Message-ID: <20170128192207.GA38136@dtor-ws>
References: <20170128184047.GA24957@dtor-ws>
 <20170128190309.GN27312@n2100.armlinux.org.uk>
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On Sat, Jan 28, 2017 at 07:03:10PM +0000, Russell King - ARM Linux wrote:
> On Sat, Jan 28, 2017 at 10:40:47AM -0800, Dmitry Torokhov wrote:
> > When converting a driver to managed resources it is desirable to be able to
> > manage all resources in the same fashion. This change allows managing
> > clocks in the same way we manage many other resources.
> > 
> > This adds the following managed APIs:
> > 
> > - devm_clk_prepare()/devm_clk_unprepare();
> > - devm_clk_enable()/devm_clk_disable();
> > - devm_clk_prepare_enable()/devm_clk_disable_unprepare().
> 
> Does it make any sense what so ever to have devm_clk_enable() and
> devm_clk_disable()?
> 
> Take a moment to think about where you use all of these.  The devm_*
> functions are there to be used in probe functions so that cleanup
> paths can be streamlined and less erroneous.  They aren't for general
> use throughout the driver.
> 
> Given that, there are two operations that you may wish to do in the
> probe path:
> 
> 1. prepare a clock (avoiding the enable because you want to perform
>    the enable elsewhere in the driver.)
> 2. prepare and enable a clock
> 
> So, does having devm_clk_enable() really make sense?  I don't think
> it does, and I suspect they'll get very little if any use.  So, I
> think best not add them until someone comes up with a good and
> wide-spread use case.

That makes sense.

Guenter, I know you are a coccinelle wizard, can you cook a script that
can find current users of clk_enable() in probe paths? Then we can make
informed decision on devm_clk_enable.

Thanks!

-- 
Dmitry