drm/nv84: use vm offsets for semaphores

We may well be making more use of semaphores in the future, having the
entire VM available makes requiring DMA objects for each and every
semaphore block unnecessary.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_fence.c

@@ -348,6 +348,9 @@ semaphore_acquire(struct nouveau_channel *chan, struct nouveau_semaphore *sema)
 		OUT_RING  (chan, 1);
 	} else
 	if (dev_priv->chipset < 0xc0) {
+		struct nouveau_vma *vma = &dev_priv->fence.bo->vma;
+		u64 offset = vma->offset + sema->mem->start;
+
 		/*
 		 * NV50 tries to be too smart and context-switch
 		 * between semaphores instead of doing a "first come,
@@ -372,8 +375,8 @@ semaphore_acquire(struct nouveau_channel *chan, struct nouveau_semaphore *sema)
 		BEGIN_RING(chan, NvSubSw, 0x0080, 1);
 		OUT_RING  (chan, 0);
 		BEGIN_RING(chan, NvSubSw, 0x0010, 4);
-		OUT_RING  (chan, upper_32_bits(sema->mem->start));
-		OUT_RING  (chan, lower_32_bits(sema->mem->start));
+		OUT_RING  (chan, upper_32_bits(offset));
+		OUT_RING  (chan, lower_32_bits(offset));
 		OUT_RING  (chan, 1);
 		OUT_RING  (chan, 1); /* ACQUIRE_EQ */
 	} else {
@@ -424,6 +427,9 @@ semaphore_release(struct nouveau_channel *chan, struct nouveau_semaphore *sema)
 		}
 	} else
 	if (dev_priv->chipset < 0xc0) {
+		struct nouveau_vma *vma = &dev_priv->fence.bo->vma;
+		u64 offset = vma->offset + sema->mem->start;
+
 		/*
 		 * Emits release and forces the card to context switch right
 		 * afterwards, there may be another channel waiting for the
@@ -435,8 +441,8 @@ semaphore_release(struct nouveau_channel *chan, struct nouveau_semaphore *sema)
 			return ret;
 
 		BEGIN_RING(chan, NvSubSw, 0x0010, 4);
-		OUT_RING  (chan, upper_32_bits(sema->mem->start));
-		OUT_RING  (chan, lower_32_bits(sema->mem->start));
+		OUT_RING  (chan, upper_32_bits(offset));
+		OUT_RING  (chan, lower_32_bits(offset));
 		OUT_RING  (chan, 1);
 		OUT_RING  (chan, 2); /* RELEASE */
 		BEGIN_RING(chan, NvSubSw, 0x0080, 1);
@@ -545,7 +551,7 @@ nouveau_fence_channel_init(struct nouveau_channel *chan)
 	OUT_RING(chan, NvSw);
 
 	/* Create a DMA object for the shared cross-channel sync area. */
-	if (USE_SEMA(dev)) {
+	if (USE_SEMA(dev) && dev_priv->chipset < 0x84) {
 		struct ttm_mem_reg *mem = &dev_priv->fence.bo->bo.mem;
 
 		ret = nouveau_gpuobj_dma_new(chan, NV_CLASS_DMA_IN_MEMORY,
@@ -565,6 +571,12 @@ nouveau_fence_channel_init(struct nouveau_channel *chan)
 			return ret;
 		BEGIN_RING(chan, NvSubSw, NV_SW_DMA_SEMAPHORE, 1);
 		OUT_RING(chan, NvSema);
+	} else {
+		ret = RING_SPACE(chan, 2);
+		if (ret)
+			return ret;
+		BEGIN_RING(chan, NvSubSw, NV_SW_DMA_SEMAPHORE, 1);
+		OUT_RING  (chan, chan->vram_handle); /* whole VM */
 	}
 
 	FIRE_RING(chan);