From c9e42b72b44acc67ede9726e6434b12ba153d901 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Tue, 28 Mar 2017 17:53:48 +0200 Subject: drm: Document kms locking a bit better The rules are getting real hard, better to dump my brain into text a bit. This is by far not complete, but I think I reasonable start at least. Some of the older kms structures would need a full doc review anyway ... Cc: Harry Wentland Reviewed-by: Harry Wentland Reviewed-by: Alex Deucher Cc: Maarten Lankhorst Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20170328155349.5972-2-daniel.vetter@ffwll.ch --- include/drm/drm_crtc.h | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'include/drm/drm_crtc.h') diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index 24dcb121bad4..c1a75a9c81c2 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -699,10 +699,12 @@ struct drm_crtc { /** * @mutex: * - * This provides a read lock for the overall crtc state (mode, dpms + * This provides a read lock for the overall CRTC state (mode, dpms * state, ...) and a write lock for everything which can be update - * without a full modeset (fb, cursor data, crtc properties ...). A full + * without a full modeset (fb, cursor data, CRTC properties ...). A full * modeset also need to grab &drm_mode_config.connection_mutex. + * + * For atomic drivers specifically this protects @state. */ struct drm_modeset_lock mutex; @@ -748,6 +750,14 @@ struct drm_crtc { * @state: * * Current atomic state for this CRTC. + * + * This is protected by @mutex. Note that nonblocking atomic commits + * access the current CRTC state without taking locks. Either by going + * through the &struct drm_atomic_state pointers, see + * for_each_crtc_in_state(), for_each_oldnew_crtc_in_state(), + * for_each_old_crtc_in_state() and for_each_new_crtc_in_state(). Or + * through careful ordering of atomic commit operations as implemented + * in the atomic helpers, see &struct drm_crtc_commit. */ struct drm_crtc_state *state; -- cgit v1.2.3