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SubjectRe: [RFC, PATCH 3/3] clk: add warnings for incorrect enable/prepare semantics
Hello Jeremy,

On Mon, Feb 07, 2011 at 02:07:57PM +0800, Jeremy Kerr 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@canonical.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);
> +
This implies the warning is only issued on clocks that have a prepare
callback. If we want to enforce the new API the warning here shouldn't
depend on clk->ops->prepare. (clk_prepare and clk_unprepare need to
be changed then to adapt the prepare_count even in the absence of
clk->ops->prepare.)

Best regards
Uwe

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