linux-kernel - Re: [RFC, PATCH 3/3] clk: add warnings for incorrect enable/prepare semantics

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Date:	Mon, 7 Feb 2011 15:29:13 +0900
From:	Jassi Brar <jassisinghbrar@...il.com>
To:	Jeremy Kerr <jeremy.kerr@...onical.com>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	linux-sh@...r.kernel.org,
	Ben Herrenschmidt <benh@...nel.crashing.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Paul Mundt <lethal@...ux-sh.org>,
	Dima Zavin <dmitriyz@...gle.com>,
	Saravana Kannan <skannan@...eaurora.org>,
	Ben Dooks <ben-linux@...ff.org>,
	Uwe Kleine-König 
	<u.kleine-koenig@...gutronix.de>,
	Russell King <linux@....linux.org.uk>
Subject: Re: [RFC, PATCH 3/3] clk: add warnings for incorrect enable/prepare semantics

On Mon, Feb 7, 2011 at 3:07 PM, Jeremy Kerr <jeremy.kerr@...onical.com> wrote:
> This change adds warnings to check for:
>
>  1) enabling a clock that hasn't been prepared; and
>
>  2) unpreparing a clock that is still enabled
>
> While the correctness can't be guaranteed, these warnings should cover
> most situations.
>
> Signed-off-by: Jeremy Kerr <jeremy.kerr@...onical.com>
>
> ---
>  drivers/clk/clk.c |    4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 51dbd33..2369959 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -35,6 +35,8 @@ void clk_unprepare(struct clk *clk)
>        if (!clk->ops->unprepare)
>                return;
>
> +       WARN_ON(clk->enable_count);
> +
>        mutex_lock(&clk->prepare_lock);
>        if (--clk->prepare_count == 0)
>                clk->ops->unprepare(clk);
> @@ -50,6 +52,8 @@ int clk_enable(struct clk *clk)
>        if (!clk->ops->enable)
>                return 0;
>
> +       WARN_ON(clk->ops->prepare && clk->prepare_count);
> +

Shouldn't the prepare_count be checked against 0 ?
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