Re: [RFC PATCH 07/15] pwm: move the enabled/disabled info to pwm_state struct
flat view
STALE4099d
From: Thierry Reding <hidden>
Date: 2015-07-20 08:11:04
Also in:
linux-arm-kernel, linux-leds, linux-pwm, linux-tegra
On Wed, Jul 01, 2015 at 10:21:53AM +0200, Boris Brezillon wrote:
quoted hunk ↗ jump to hunk
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 <redacted> --- 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
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