From d14341cb22e37f52070cd92b707fec5e08038e96 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 17 Jan 2012 00:31:43 +0000
Subject: [PATCH] sna: Add a render ring detiling read path

For SNB, in case you really, really want to use GPU detiling and not
incur the ring switch. Tweaking when to just mmap the target seems to
gain most anyway...

The ulterior motive is that this provides fallback paths for avoiding
the use of TILING_Y with GTT mmaps which is broken on 855gm.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 src/sna/sna_io.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 68 insertions(+), 2 deletions(-)

diff --git a/src/sna/sna_io.c b/src/sna/sna_io.c
index 6b085322..4174b0ed 100644
--- a/src/sna/sna_io.c
+++ b/src/sna/sna_io.c
@@ -89,8 +89,9 @@ void sna_read_boxes(struct sna *sna,
 {
 	struct kgem *kgem = &sna->kgem;
 	struct kgem_bo *dst_bo;
-	int tmp_nbox;
+	BoxRec extents;
 	const BoxRec *tmp_box;
+	int tmp_nbox;
 	char *src;
 	void *ptr;
 	int src_pitch, cpp, offset;
@@ -123,7 +124,8 @@ void sna_read_boxes(struct sna *sna,
 
 	if (DEBUG_NO_IO || kgem->wedged ||
 	    !kgem_bo_map_will_stall(kgem, src_bo) ||
-	    src_bo->tiling != I915_TILING_X) {
+	    src_bo->tiling == I915_TILING_NONE) {
+fallback:
 		read_boxes_inplace(kgem,
 				   src_bo, src_dx, src_dy,
 				   dst, dst_dx, dst_dy,
@@ -131,6 +133,70 @@ void sna_read_boxes(struct sna *sna,
 		return;
 	}
 
+	/* Is it worth detiling? */
+	extents = box[0];
+	for (n = 1; n < nbox; n++) {
+		if (box[n].x1 < extents.x1)
+			extents.x1 = box[n].x1;
+		if (box[n].x2 > extents.x2)
+			extents.x2 = box[n].x2;
+
+		if (box[n].y1 < extents.y1)
+			extents.y1 = box[n].y1;
+		if (box[n].y2 > extents.y2)
+			extents.y2 = box[n].y2;
+	}
+	if ((extents.y2 - extents.y1) * src_bo->pitch < 4096)
+		goto fallback;
+
+	/* Try to avoid switching rings... */
+	if (src_bo->tiling == I915_TILING_Y || kgem->ring == KGEM_RENDER) {
+		PixmapRec tmp;
+
+		tmp.drawable.width  = extents.x2 - extents.x1;
+		tmp.drawable.height = extents.y2 - extents.y1;
+		tmp.drawable.depth  = dst->drawable.depth;
+		tmp.drawable.bitsPerPixel = dst->drawable.bitsPerPixel;
+		tmp.devPrivate.ptr = NULL;
+
+		assert(tmp.drawable.width);
+		assert(tmp.drawable.height);
+
+		dst_bo = kgem_create_buffer_2d(kgem,
+					       tmp.drawable.width,
+					       tmp.drawable.height,
+					       tmp.drawable.bitsPerPixel,
+					       KGEM_BUFFER_LAST,
+					       &ptr);
+		if (!dst_bo)
+			goto fallback;
+
+		if (!sna->render.copy_boxes(sna, GXcopy,
+					    dst, src_bo, src_dx, src_dy,
+					    &tmp, dst_bo, -extents.x1, -extents.y1,
+					    box, nbox)) {
+			kgem_bo_destroy(&sna->kgem, dst_bo);
+			goto fallback;
+		}
+
+		kgem_bo_submit(&sna->kgem, dst_bo);
+		kgem_buffer_read_sync(kgem, dst_bo);
+
+		for (n = 0; n < nbox; n++) {
+			memcpy_blt(ptr, dst->devPrivate.ptr, tmp.drawable.bitsPerPixel,
+				   dst_bo->pitch, dst->devKind,
+				   box[n].x1 - extents.x1,
+				   box[n].y1 - extents.y1,
+				   box[n].x1 + dst_dx,
+				   box[n].y1 + dst_dy,
+				   box[n].x2 - box[n].x1,
+				   box[n].y2 - box[n].y1);
+		}
+
+		kgem_bo_destroy(&sna->kgem, dst_bo);
+		return;
+	}
+
 	/* count the total number of bytes to be read and allocate a bo */
 	cpp = dst->drawable.bitsPerPixel / 8;
 	offset = 0;