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SubjectRe: [PATCH v5 2/2] pwm: core: Set enable state properly on failed call to enable
On Wed, Jan 07, 2015 at 11:42:51AM -0800, Jonathan Richardson wrote:
> The pwm_enable function didn't clear the enabled bit if a call to a
> clients enable function returned an error. The result was that the state
> of the pwm core was wrong. Clearing the bit when enable returns an error
> ensures the state is properly set.
>
> Tested-by: Jonathan Richardson <jonathar@broadcom.com>
> Signed-off-by: Jonathan Richardson <jonathar@broadcom.com>
> ---
> drivers/pwm/core.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
> index f28c4ce..c33e24f 100644
> --- a/drivers/pwm/core.c
> +++ b/drivers/pwm/core.c
> @@ -477,8 +477,14 @@ EXPORT_SYMBOL_GPL(pwm_set_polarity);
> */
> int pwm_enable(struct pwm_device *pwm)
> {
> - if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags))
> - return pwm->chip->ops->enable(pwm->chip, pwm);
> + int err;
> +
> + if (pwm && !test_and_set_bit(PWMF_ENABLED, &pwm->flags)) {
> + err = pwm->chip->ops->enable(pwm->chip, pwm);
> + if (err)
> + clear_bit(PWMF_ENABLED, &pwm->flags);
> + return err;
> + }
>
> return pwm ? 0 : -EINVAL;

Seems fine in principle, but somewhat messy. Can we do the following:

int pwm_enable(struct pwm_device *pwm)
{
int err;

if (!pwm)
return -EINVAL;

if (!test_and_set_bit(PWMF_ENABLED, &pwm->flags)) {
err = pwm->chip->ops->enable(pwm->chip, pwm);
if (err) {
clear_bit(PWMF_ENABLED, &pwm->flags);
return err;
}
}

return 0;
}

Otherwise:

Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Thanks.

--
Dmitry


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