| Message ID | 1435738921-25027-8-git-send-email-boris.brezillon@free-electrons.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jul 01, 2015 at 10:21:53AM +0200, Boris Brezillon wrote: > Prepare the transition to PWM atomic update by moving the enabled/disabled > state into the pwm_state struct. This way we can easily update the whole > PWM state by copying the new state in the ->state field. > > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> > --- > drivers/pwm/core.c | 15 ++++++++++++--- > include/linux/pwm.h | 6 +++--- > 2 files changed, 15 insertions(+), 6 deletions(-) > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index a6bc8e6..3e830ce 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -474,8 +474,15 @@ 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); > + if (pwm && !pwm_is_enabled(pwm)) { > + int err; > + > + err = pwm->chip->ops->enable(pwm->chip, pwm); > + if (!err) > + pwm->state.enabled = true; > + > + return err; > + } Technically there's now a race between the pwm_is_enabled() and pwm->state.enabled = true; statements, but as discussed in the cover letter I think that's fine because of the assumptions about concurrent usage of PWMs. The most important check (PWMF_REQUESTED) is still atomic, so it is still up to drivers to properly lock concurrent access to a PWM device and the core will make sure that a device can only be requested once. Thierry
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index a6bc8e6..3e830ce 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -474,8 +474,15 @@ 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); + if (pwm && !pwm_is_enabled(pwm)) { + int err; + + err = pwm->chip->ops->enable(pwm->chip, pwm); + if (!err) + pwm->state.enabled = true; + + return err; + } return pwm ? 0 : -EINVAL; } @@ -487,8 +494,10 @@ EXPORT_SYMBOL_GPL(pwm_enable); */ void pwm_disable(struct pwm_device *pwm) { - if (pwm && test_and_clear_bit(PWMF_ENABLED, &pwm->flags)) + if (pwm && pwm_is_enabled(pwm)) { pwm->chip->ops->disable(pwm->chip, pwm); + pwm->state.enabled = false; + } } EXPORT_SYMBOL_GPL(pwm_disable); diff --git a/include/linux/pwm.h b/include/linux/pwm.h index bed7234..fd3e0f0 100644 --- a/include/linux/pwm.h +++ b/include/linux/pwm.h @@ -75,14 +75,14 @@ enum pwm_polarity { enum { PWMF_REQUESTED = 1 << 0, - PWMF_ENABLED = 1 << 1, - PWMF_EXPORTED = 1 << 2, + PWMF_EXPORTED = 1 << 1, }; struct pwm_state { unsigned int period; /* in nanoseconds */ unsigned int duty_cycle; /* in nanoseconds */ enum pwm_polarity polarity; + bool enabled; }; struct pwm_device { @@ -98,7 +98,7 @@ struct pwm_device { static inline bool pwm_is_enabled(const struct pwm_device *pwm) { - return test_bit(PWMF_ENABLED, &pwm->flags); + return pwm->state.enabled; } static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
Prepare the transition to PWM atomic update by moving the enabled/disabled state into the pwm_state struct. This way we can easily update the whole PWM state by copying the new state in the ->state field. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> --- drivers/pwm/core.c | 15 ++++++++++++--- include/linux/pwm.h | 6 +++--- 2 files changed, 15 insertions(+), 6 deletions(-)