diff options
| author | Uwe Kleine-König <u.kleine-koenig@baylibre.com> | 2025-06-24 12:05:00 +0200 |
|---|---|---|
| committer | Uwe Kleine-König <ukleinek@kernel.org> | 2025-07-07 08:39:36 +0200 |
| commit | 10e9b32d9a14edbbed902dd5447a1ca3cd487935 (patch) | |
| tree | 660192c489f0ff87154c9fdc1eb10329d3240324 | |
| parent | 2c06a2178926993f77e52f77e6b0c540e3d771ce (diff) | |
docs: pwm: Adapt Locking paragraph to reality
We have the distinction between pwm_apply_atomic() and
pwm_apply_might_sleep() since commit c748a6d77c06 (pwm: Rename
pwm_apply_state() to pwm_apply_might_sleep()) contained in v6.8-rc1.
Locking in the core was introduced in commit 1cc2e1faafb3 ("pwm: Add
more locking", contained in v6.13-rc1) to serialize per-chip callbacks
and device removal.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20250624100500.1429163-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>
| -rw-r--r-- | Documentation/driver-api/pwm.rst | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/Documentation/driver-api/pwm.rst b/Documentation/driver-api/pwm.rst index b41b1c56477f..0d27a40f5818 100644 --- a/Documentation/driver-api/pwm.rst +++ b/Documentation/driver-api/pwm.rst @@ -173,10 +173,15 @@ Locking ------- The PWM core list manipulations are protected by a mutex, so pwm_get() -and pwm_put() may not be called from an atomic context. Currently the -PWM core does not enforce any locking to pwm_enable(), pwm_disable() and -pwm_config(), so the calling context is currently driver specific. This -is an issue derived from the former barebone API and should be fixed soon. +and pwm_put() may not be called from an atomic context. +Most functions in the PWM consumer API might sleep and so must not be called +from atomic context. The notable exception is pwm_apply_atomic() which has the +same semantics as pwm_apply_might_sleep() but can be called from atomic context. +(The price for that is that it doesn't work for all PWM devices, use +pwm_might_sleep() to check if a given PWM supports atomic operation. + +Locking in the PWM core ensures that callbacks related to a single chip are +serialized. Helpers ------- |