From 7141fd3e5ba90d09d2138ff1bbefd7cc43a82e94 Mon Sep 17 00:00:00 2001
From: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Wed, 21 Jun 2017 11:16:27 +0200
Subject: [PATCH] drm/atomic-helper: Simplify commit tracking locking
Git-commit: 7141fd3e5ba90d09d2138ff1bbefd7cc43a82e94
Patch-mainline: v4.14-rc1
References: FATE#322643 bsc#1055900

The crtc->commit_lock only protects commit_list and commit_entry. If
we chase the pointer from the drm_atomic_state update structure, then
we don't need any locks (since we hold a reference already).

Simplify the locking accordingly.

Noticed while reviewing a patch from Boris.

Cc: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170621091627.30837-1-daniel.vetter@ffwll.ch
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/drm_atomic_helper.c |    7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1721,9 +1721,7 @@ void drm_atomic_helper_commit_hw_done(st
 
 		/* backend must have consumed any event by now */
 		WARN_ON(new_crtc_state->event);
-		spin_lock(&crtc->commit_lock);
 		complete_all(&commit->hw_done);
-		spin_unlock(&crtc->commit_lock);
 	}
 }
 EXPORT_SYMBOL(drm_atomic_helper_commit_hw_done);
@@ -1752,7 +1750,6 @@ void drm_atomic_helper_commit_cleanup_do
 		if (WARN_ON(!commit))
 			continue;
 
-		spin_lock(&crtc->commit_lock);
 		complete_all(&commit->cleanup_done);
 		WARN_ON(!try_wait_for_completion(&commit->hw_done));
 
@@ -1762,8 +1759,6 @@ void drm_atomic_helper_commit_cleanup_do
 		if (try_wait_for_completion(&commit->flip_done))
 			goto del_commit;
 
-		spin_unlock(&crtc->commit_lock);
-
 		/* We must wait for the vblank event to signal our completion
 		 * before releasing our reference, since the vblank work does
 		 * not hold a reference of its own. */
@@ -1773,8 +1768,8 @@ void drm_atomic_helper_commit_cleanup_do
 			DRM_ERROR("[CRTC:%d:%s] flip_done timed out\n",
 				  crtc->base.id, crtc->name);
 
-		spin_lock(&crtc->commit_lock);
 del_commit:
+		spin_lock(&crtc->commit_lock);
 		list_del(&commit->commit_entry);
 		spin_unlock(&crtc->commit_lock);
 	}