Explain better when the drm_modeset_acquire_ctx parameter can be skipped for drm_modeset_lock() call. Signed-off-by: Liviu Dudau <Liviu.Dudau@xxxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> --- drivers/gpu/drm/drm_modeset_lock.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_modeset_lock.c b/drivers/gpu/drm/drm_modeset_lock.c index 64ef09a6cccb..af4e906c630d 100644 --- a/drivers/gpu/drm/drm_modeset_lock.c +++ b/drivers/gpu/drm/drm_modeset_lock.c @@ -52,7 +52,12 @@ * drm_modeset_drop_locks(&ctx); * drm_modeset_acquire_fini(&ctx); * - * On top of of these per-object locks using &ww_mutex there's also an overall + * If all that is needed is a single modeset lock, then the &struct + * drm_modeset_acquire_ctx is not needed and the locking can be simplified + * by passing a NULL instead of ctx in the drm_modeset_lock() + * call and, when done, by calling drm_modeset_unlock(). + * + * On top of these per-object locks using &ww_mutex there's also an overall * &drm_mode_config.mutex, for protecting everything else. Mostly this means * probe state of connectors, and preventing hotplug add/removal of connectors. * @@ -313,11 +318,14 @@ EXPORT_SYMBOL(drm_modeset_lock_init); * @lock: lock to take * @ctx: acquire ctx * - * If ctx is not NULL, then its ww acquire context is used and the + * If @ctx is not NULL, then its ww acquire context is used and the * lock will be tracked by the context and can be released by calling * drm_modeset_drop_locks(). If -EDEADLK is returned, this means a * deadlock scenario has been detected and it is an error to attempt * to take any more locks without first calling drm_modeset_backoff(). + * + * If @ctx is NULL then the function call behaves like a normal, + * non-nesting mutex_lock() call. */ int drm_modeset_lock(struct drm_modeset_lock *lock, struct drm_modeset_acquire_ctx *ctx) -- 2.13.2 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
