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drivers: pwm: clarify API details

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Clarify the PWM pwm_pin_set_cycles() function API details.

The API aims for synchronous (glitch-free) updates of the PWM period and
pulse width, but not all PWM controllers support this.

Similarly, the API aims for independance between channels on
multi-channel PWM controllers, but not all PWM controllers support this.

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
This commit is contained in:
Henrik Brix Andersen 2021-08-17 16:52:11 +02:00 • committed by Christopher Friedt
commit d2ddd379c9
1 changed files with 12 additions and 0 deletions
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12
include/drivers/pwm.h
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@ -152,6 +152,18 @@ __subsystem struct pwm_driver_api {
/**
* @brief Set the period and pulse width for a single PWM output.
*
* The PWM period and pulse width will synchronously be set to the new values
* without glitches in the PWM signal, but the call will not block for the
* change to take effect.
*
* @note Not all PWM controllers support synchronous, glitch-free updates of the
* PWM period and pulse width. Depending on the hardware, changing the PWM
* period and/or pulse width may cause a glitch in the generated PWM signal.
*
* @note Some multi-channel PWM controllers share the PWM period across all
* channels. Depending on the hardware, changing the PWM period for one channel
* may affect the PWM period for the other channels of the same PWM controller.
*
* Passing 0 as @p pulse will cause the pin to be driven to a constant
* inactive level.
* Passing a non-zero @p pulse equal to @p period will cause the pin