Revert "drm/nouveau: inform userspace of new kernel subchannel requirements"

This reverts commit a81f15499887d3f9f24ec70bb9b7e778942a6b7b.

Gah, we have a released userspace component using fixed subc assignment
that conflicts with this.  To avoid breaking ABI this needs to be
reverted.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_channel.c

@@ -436,11 +436,18 @@ nouveau_ioctl_fifo_alloc(struct drm_device *dev, void *data,
 	}
 
 	if (dev_priv->card_type < NV_C0) {
-		init->subchan[0].handle = NvSw;
-		init->subchan[0].grclass = NV_SW;
-		init->nr_subchan = 1;
+		init->subchan[0].handle = NvM2MF;
+		if (dev_priv->card_type < NV_50)
+			init->subchan[0].grclass = 0x0039;
+		else
+			init->subchan[0].grclass = 0x5039;
+		init->subchan[1].handle = NvSw;
+		init->subchan[1].grclass = NV_SW;
+		init->nr_subchan = 2;
 	} else {
-		init->nr_subchan = 0;
+		init->subchan[0].handle  = 0x9039;
+		init->subchan[0].grclass = 0x9039;
+		init->nr_subchan = 1;
 	}
 
 	/* Named memory object area */

drivers/gpu/drm/nouveau/nouveau_dma.h

@@ -48,8 +48,8 @@ void nv50_dma_push(struct nouveau_channel *, struct nouveau_bo *,
 
 /* Hardcoded object assignments to subchannels (subchannel id). */
 enum {
-	NvSubSw		= 0,
-	NvSubM2MF	= 1,
+	NvSubM2MF	= 0,
+	NvSubSw		= 1,
 	NvSub2D		= 2,
 	NvSubCtxSurf2D  = 2,
 	NvSubGdiRect    = 3,