radeon: workaround pinning failure on low ram gpu

From Jerome Glisse
9043b83c07a1899bbb094fb4f1c889aab4756a6a in ubuntu 3.8
97b6ff6be9da7675aab339334fda996d6c5077d9 in mainline linux

1 files changed, 29 insertions, 1 deletions

diff --git a/sys/dev/pci/drm/radeon/radeon_legacy_crtc.c b/sys/dev/pci/drm/radeon/radeon_legacy_crtc.c
index 4c2c1ab73f0..c4236800b75 100644
--- a/sys/dev/pci/drm/radeon/radeon_legacy_crtc.c
+++ b/sys/dev/pci/drm/radeon/radeon_legacy_crtc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: radeon_legacy_crtc.c,v 1.2 2013/12/05 13:29:56 kettenis Exp $	*/
+/*	$OpenBSD: radeon_legacy_crtc.c,v 1.3 2014/02/10 01:22:10 jsg Exp $	*/
 /*
  * Copyright 2007-8 Advanced Micro Devices, Inc.
  * Copyright 2008 Red Hat Inc.
@@ -423,6 +423,7 @@ int radeon_crtc_do_set_base(struct drm_crtc *crtc,
 	/* Pin framebuffer & get tilling informations */
 	obj = radeon_fb->obj;
 	rbo = gem_to_radeon_bo(obj);
+retry:
 	r = radeon_bo_reserve(rbo, false);
 	if (unlikely(r != 0))
 		return r;
@@ -431,6 +432,33 @@ int radeon_crtc_do_set_base(struct drm_crtc *crtc,
 				     &base);
 	if (unlikely(r != 0)) {
 		radeon_bo_unreserve(rbo);
+
+		/* On old GPU like RN50 with little vram pining can fails because
+		 * current fb is taking all space needed. So instead of unpining
+		 * the old buffer after pining the new one, first unpin old one
+		 * and then retry pining new one.
+		 *
+		 * As only master can set mode only master can pin and it is
+		 * unlikely the master client will race with itself especialy
+		 * on those old gpu with single crtc.
+		 *
+		 * We don't shutdown the display controller because new buffer
+		 * will end up in same spot.
+		 */
+		if (!atomic && fb && fb != crtc->fb) {
+			struct radeon_bo *old_rbo;
+			unsigned long nsize, osize;
+
+			old_rbo = gem_to_radeon_bo(to_radeon_framebuffer(fb)->obj);
+			osize = radeon_bo_size(old_rbo);
+			nsize = radeon_bo_size(rbo);
+			if (nsize <= osize && !radeon_bo_reserve(old_rbo, false)) {
+				radeon_bo_unpin(old_rbo);
+				radeon_bo_unreserve(old_rbo);
+				fb = NULL;
+				goto retry;
+			}
+		}
 		return -EINVAL;
 	}
 	radeon_bo_get_tiling_flags(rbo, &tiling_flags, NULL);