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    SubjectRe: [PATCH 56/62] watchdog: tangox_wdt: Convert to use device managed functions
    On Wed, Jan 11, 2017 at 01:31:47PM +0100, Marc Gonzalez wrote:
    > On 11/01/2017 11:52, Guenter Roeck wrote:
    >
    > > On 01/11/2017 01:07 AM, Marc Gonzalez wrote:
    > >
    > >>> @@ -134,12 +134,15 @@ static int tangox_wdt_probe(struct platform_device *pdev)
    > >>> err = clk_prepare_enable(dev->clk);
    > >>> if (err)
    > >>> return err;
    > >>> + err = devm_add_action_or_reset(&pdev->dev,
    > >>> + (void(*)(void *))clk_disable_unprepare,
    > >>> + dev->clk);
    > >>> + if (err)
    > >>> + return err;

    This looks wrong. There is no clk_unprepare_disable when
    devm_add_action_or_reset fails.

    > >>
    > >> Hello Guenter,
    > >>
    > >> I would rather avoid the function pointer cast.
    > >> How about defining an auxiliary function for the cleanup action?
    > >>
    > >> clk_disable_unprepare() is static inline, so gcc will have to
    > >> define an auxiliary function either way. What do you think?
    > >
    > > Not really. It would just make it more complicated to replace the
    > > call with devm_clk_prepare_enable(), should it ever find its way
    > > into the light of day.
    >
    > More complicated, because the cleanup function will have to be deleted later?
    > The compiler will warn if someone forgets to do that.
    >
    > In my opinion, it's not a good idea to rely on the fact that casting
    > void(*)(struct clk *clk) to void(*)(void *) is likely to work as expected
    > on most platforms. (It has undefined behavior, strictly speaking.)

    I would expect it to work on all (Linux) platforms. Anyhow, I wonder if
    there couldn't be found a better solution.

    If in the end it looks like the following that would be good I think:

    clk = devm_clk_get(...);
    if (IS_ERR(clk))
    ...

    ret = devm_clk_prepare_enable(clk)
    if (ret)
    return ret;

    ...

    Best regards
    Uwe

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

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