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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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