linux-kernel - Re: Automatic clock disabling on clk

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Message-ID: <55528B84.5050700@codeaurora.org>
Date:	Tue, 12 May 2015 16:23:48 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Sascha Hauer <s.hauer@...gutronix.de>,
	Mike Turquette <mturquette@...aro.org>
CC:	linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, kernel@...gutronix.de
Subject: Re: Automatic clock disabling on clk_put()

On 05/10/15 23:01, Sascha Hauer wrote:
> Hi,
>
> Since we now have per-user clks we could automatically disable clks on
> clk_put() to make the drivers errors paths easier. AFAIR that was one
> of the motivations to switch to per user clks. Is this just not yet
> implemented or are there problems implementing this?
>
>

I don't recall that as being a motivation for per-user clks. The
documentation explicitly states:

 * Note: drivers must ensure that all clk_enable calls made on this
 * clock source are balanced by clk_disable calls prior to calling
 * this function.

so it seems that such a behavior would be an API change. Is it really
that hard to call clk_disable_unprepare() on a clock at the end of an
error path? Maybe you could add a devm_clk_get_prepare_enable() that
does what you want and then call clk_disable_unprepare on the exit path?

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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