linux-kernel - Re: [PATCH v1] clk: Add devm_clk_{prepare,enable,prepare

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Message-ID: <c7414301-da0d-cd4d-237d-34277f5ee1d2@free.fr>
Date:   Mon, 25 Nov 2019 14:10:21 +0100
From:   Marc Gonzalez <marc.w.gonzalez@...e.fr>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>
Cc:     Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        linux-clk <linux-clk@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] clk: Add devm_clk_{prepare,enable,prepare_enable}

On 25/11/2019 13:55, Russell King - ARM Linux admin wrote:

> It's also worth reading https://lore.kernel.org/patchwork/patch/755667/
> and considering whether you really are using the clk_prepare() and
> clk_enable() APIs correctly.  Wanting these devm functions suggests
> you aren't...

In that older thread, you wrote:

> If you take the view that trying to keep clocks disabled is a good way
> to save power, then you'd have the clk_prepare() or maybe
> clk_prepare_enable() in your run-time PM resume handler, or maybe even
> deeper in the driver... the original design goal of the clk API was to
> allow power saving and clock control.
> 
> With that in mind, getting and enabling the clock together in the
> probe function didn't make sense.
> 
> I feel that aspect has been somewhat lost, and people now regard much
> of the clk API as a bit of a probe-time nuisance.

In the few drivers I've written, I call clk_prepare_enable() at probe.

And since clk_prepare_enable() is the only non-devm function in probe,
I need either a remove function, or an explicit registration step.

You seem to be saying I'm using the clk API in the wrong way?

Regards.