[PATCH 5/8] drm/mgag200: Pin framebuffer BO during dirty update

[Thomas Zimmermann]

Another explicit lock operation of a GEM VRAM BO is located in mgag200's
framebuffer update code. Instead of locking the BO, we pin it to wherever
it is.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/mgag200/mgag200_fb.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/mgag200/mgag200_fb.c b/drivers/gpu/drm/mgag200/mgag200_fb.c
index 97c575a9a86f..dbcf179a120c 100644
--- a/drivers/gpu/drm/mgag200/mgag200_fb.c
+++ b/drivers/gpu/drm/mgag200/mgag200_fb.c
@@ -26,7 +26,7 @@ static void mga_dirty_update(struct mga_fbdev *mfbdev,
 	struct drm_gem_vram_object *gbo;
 	int src_offset, dst_offset;
 	int bpp = mfbdev->mfb.base.format->cpp[0];
-	int ret = -EBUSY;
+	int ret;
 	u8 *dst;
 	bool unmap = false;
 	bool store_for_later = false;
@@ -36,18 +36,20 @@ static void mga_dirty_update(struct mga_fbdev *mfbdev,
 	obj = mfbdev->mfb.obj;
 	gbo = drm_gem_vram_of_gem(obj);
 
-	/* Try to lock the BO. If we fail with -EBUSY then
-	 * the BO is being moved and we should store up the
-	 * damage until later.
+	/* We pin the BO to system memory so it won't be moved during
+	 * the update and doesn't waste video ram. If the BO is already
+	 * located in VRAM, the pin operation will simply increment the
+	 * pin count.
 	 */
-	if (drm_can_sleep())
-		ret = drm_gem_vram_lock(gbo, true);
-	if (ret) {
-		if (ret != -EBUSY)
-			return;
-
+	if (drm_can_sleep()) {
+		ret = drm_gem_vram_pin(gbo, TTM_PL_FLAG_SYSTEM);
+		if (ret) {
+			if (ret != -EBUSY)
+				return;
+			store_for_later = true;
+		}
+	} else
 		store_for_later = true;
-	}
 
 	x2 = x + width - 1;
 	y2 = y + height - 1;
@@ -100,7 +102,7 @@ static void mga_dirty_update(struct mga_fbdev *mfbdev,
 		drm_gem_vram_kunmap(gbo);
 
 out:
-	drm_gem_vram_unlock(gbo);
+	drm_gem_vram_unpin(gbo);
 }
 
 static void mga_fillrect(struct fb_info *info,
-- 
2.21.0