drm/nouveau: Add module options to disable acceleration.

noaccel=1 disables all acceleration and doesn't even attempt
initialising PGRAPH+PFIFO, nofbaccel=1 only makes fbcon unaccelerated.
Signed-off-by: Marcin Kościelnicki <koriakin@0x04.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_drv.c

@@ -75,6 +75,14 @@ MODULE_PARM_DESC(ignorelid, "Ignore ACPI lid status");
 int nouveau_ignorelid = 0;
 module_param_named(ignorelid, nouveau_ignorelid, int, 0400);
 
+MODULE_PARM_DESC(noagp, "Disable all acceleration");
+int nouveau_noaccel = 0;
+module_param_named(noaccel, nouveau_noaccel, int, 0400);
+
+MODULE_PARM_DESC(noagp, "Disable fbcon acceleration");
+int nouveau_nofbaccel = 0;
+module_param_named(nofbaccel, nouveau_nofbaccel, int, 0400);
+
 MODULE_PARM_DESC(tv_norm, "Default TV norm.\n"
 		 "\t\tSupported: PAL, PAL-M, PAL-N, PAL-Nc, NTSC-M, NTSC-J,\n"
 		 "\t\t\thd480i, hd480p, hd576i, hd576p, hd720p, hd1080i.\n"

drivers/gpu/drm/nouveau/nouveau_drv.h

@@ -678,6 +678,8 @@ extern int nouveau_reg_debug;
 extern char *nouveau_vbios;
 extern int nouveau_ctxfw;
 extern int nouveau_ignorelid;
+extern int nouveau_nofbaccel;
+extern int nouveau_noaccel;
 
 /* nouveau_state.c */
 extern void nouveau_preclose(struct drm_device *dev, struct drm_file *);

drivers/gpu/drm/nouveau/nouveau_fbcon.c

@@ -267,8 +267,12 @@ nouveau_fbcon_create(struct drm_device *dev, uint32_t fb_width,
 	dev_priv->fbdev_info = info;
 
 	strcpy(info->fix.id, "nouveaufb");
-	info->flags = FBINFO_DEFAULT | FBINFO_HWACCEL_COPYAREA |
-		      FBINFO_HWACCEL_FILLRECT | FBINFO_HWACCEL_IMAGEBLIT;
+	if (nouveau_nofbaccel)
+		info->flags = FBINFO_DEFAULT | FBINFO_HWACCEL_DISABLED;
+	else
+		info->flags = FBINFO_DEFAULT | FBINFO_HWACCEL_COPYAREA |
+			      FBINFO_HWACCEL_FILLRECT |
+			      FBINFO_HWACCEL_IMAGEBLIT;
 	info->fbops = &nouveau_fbcon_ops;
 	info->fix.smem_start = dev->mode_config.fb_base + nvbo->bo.offset -
 			       dev_priv->vm_vram_base;
@@ -316,7 +320,7 @@ nouveau_fbcon_create(struct drm_device *dev, uint32_t fb_width,
 	par->nouveau_fb = nouveau_fb;
 	par->dev = dev;
 
-	if (dev_priv->channel) {
+	if (dev_priv->channel && !nouveau_nofbaccel) {
 		switch (dev_priv->card_type) {
 		case NV_50:
 			nv50_fbcon_accel_init(info);

drivers/gpu/drm/nouveau/nouveau_state.c

@@ -427,15 +427,19 @@ nouveau_card_init(struct drm_device *dev)
 	if (ret)
 		goto out_timer;
 
-	/* PGRAPH */
-	ret = engine->graph.init(dev);
-	if (ret)
-		goto out_fb;
+	if (nouveau_noaccel)
+		engine->graph.accel_blocked = true;
+	else {
+		/* PGRAPH */
+		ret = engine->graph.init(dev);
+		if (ret)
+			goto out_fb;
 
-	/* PFIFO */
-	ret = engine->fifo.init(dev);
-	if (ret)
-		goto out_graph;
+		/* PFIFO */
+		ret = engine->fifo.init(dev);
+		if (ret)
+			goto out_graph;
+	}
 
 	/* this call irq_preinstall, register irq handler and
 	 * call irq_postinstall
@@ -479,9 +483,11 @@ nouveau_card_init(struct drm_device *dev)
 out_irq:
 	drm_irq_uninstall(dev);
 out_fifo:
-	engine->fifo.takedown(dev);
+	if (!nouveau_noaccel)
+		engine->fifo.takedown(dev);
 out_graph:
-	engine->graph.takedown(dev);
+	if (!nouveau_noaccel)
+		engine->graph.takedown(dev);
 out_fb:
 	engine->fb.takedown(dev);
 out_timer:
@@ -518,8 +524,10 @@ static void nouveau_card_takedown(struct drm_device *dev)
 			dev_priv->channel = NULL;
 		}
 
-		engine->fifo.takedown(dev);
-		engine->graph.takedown(dev);
+		if (!nouveau_noaccel) {
+			engine->fifo.takedown(dev);
+			engine->graph.takedown(dev);
+		}
 		engine->fb.takedown(dev);
 		engine->timer.takedown(dev);
 		engine->mc.takedown(dev);