diff options
| author | Sean Young <sean@mess.org> | 2023-12-19 16:30:27 +0000 |
|---|---|---|
| committer | Thierry Reding <thierry.reding@gmail.com> | 2023-12-20 16:07:06 +0100 |
| commit | 7170d3beafc2373dd76b6b5d6e617d89e4e42b8b (patch) | |
| tree | 0c5b06c6031df723f752de7120acf85a915c458a /Documentation/driver-api | |
| parent | 752193da3f8b0aa819a27fc741d46ab046be315e (diff) | |
pwm: Make it possible to apply PWM changes in atomic context
Some PWM devices require sleeping, for example if the pwm device is
connected over I2C. However, many PWM devices could be used from atomic
context, e.g. memory mapped PWM. This is useful for, for example, the
pwm-ir-tx driver which requires precise timing. Sleeping causes havoc
with the generated IR signal.
Since not all PWM devices can support atomic context, we also add a
pwm_might_sleep() function to check if is not supported.
Signed-off-by: Sean Young <sean@mess.org>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/pwm.rst | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/driver-api/pwm.rst b/Documentation/driver-api/pwm.rst index f1d8197c8c43..3c28ccc4b611 100644 --- a/Documentation/driver-api/pwm.rst +++ b/Documentation/driver-api/pwm.rst @@ -46,6 +46,15 @@ After being requested, a PWM has to be configured using:: This API controls both the PWM period/duty_cycle config and the enable/disable state. +PWM devices can be used from atomic context, if the PWM does not sleep. You +can check if this the case with:: + + bool pwm_might_sleep(struct pwm_device *pwm); + +If false, the PWM can also be configured from atomic context with:: + + int pwm_apply_atomic(struct pwm_device *pwm, struct pwm_state *state); + As a consumer, don't rely on the output's state for a disabled PWM. If it's easily possible, drivers are supposed to emit the inactive state, but some drivers cannot. If you rely on getting the inactive state, use .duty_cycle=0, |