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drm: Improve kerneldoc for drm_modeset_lock 

Explain better when the drm_modeset_acquire_ctx parameter can
be skipped for drm_modeset_lock() call.

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20170720160748.12856-1-Liviu.Dudau@arm.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Liviu Dudau 2017-07-20 17:07:48 +01:00 committed by Daniel Vetter
parent 14693a0816
commit fc2157b6ed
1 changed files with 10 additions and 2 deletions
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12
drivers/gpu/drm/drm_modeset_lock.c
View File

@ -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)