From: Marcin Slusarz <marcin.slusarz@gmail.com>
Date: Fri, 5 Oct 2012 10:26:32 +0000 (+0200)
Subject: drm/nouveau: handle same-fb page flips
X-Git-Tag: firefly_0821_release~3680^2~1722^2~7^2~8
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2c14575f99ddd5b8384c5b460687ceba181900d8;p=firefly-linux-kernel-4.4.55.git

drm/nouveau: handle same-fb page flips

It's questionable use case, but weston/wayland already relies on this
behaviour, and other drivers don't care about it, so it's a matter of
compatibility.  Without it, process invoking such page flip hangs in
unkillable state, trying to reserve the same buffer twice.

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
---

diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c
index 61f370d000e9..53ee3037d309 100644
--- a/drivers/gpu/drm/nouveau/nouveau_display.c
+++ b/drivers/gpu/drm/nouveau/nouveau_display.c
@@ -530,9 +530,11 @@ nouveau_page_flip_reserve(struct nouveau_bo *old_bo,
 	if (ret)
 		goto fail;
 
-	ret = ttm_bo_reserve(&old_bo->bo, false, false, false, 0);
-	if (ret)
-		goto fail_unreserve;
+	if (likely(old_bo != new_bo)) {
+		ret = ttm_bo_reserve(&old_bo->bo, false, false, false, 0);
+		if (ret)
+			goto fail_unreserve;
+	}
 
 	return 0;
 
@@ -551,8 +553,10 @@ nouveau_page_flip_unreserve(struct nouveau_bo *old_bo,
 	nouveau_bo_fence(new_bo, fence);
 	ttm_bo_unreserve(&new_bo->bo);
 
-	nouveau_bo_fence(old_bo, fence);
-	ttm_bo_unreserve(&old_bo->bo);
+	if (likely(old_bo != new_bo)) {
+		nouveau_bo_fence(old_bo, fence);
+		ttm_bo_unreserve(&old_bo->bo);
+	}
 
 	nouveau_bo_unpin(old_bo);
 }