drm/nouveau: headless mode by default if pci class != vga display

This is to prevent nouveau from taking over the console on headless boards
such as Tesla.

Backport of upstream commit: e412e95

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpu/drm/nouveau/nouveau_drv.c

@@ -488,9 +488,7 @@ static int __init nouveau_init(void)
 #ifdef CONFIG_VGA_CONSOLE
 		if (vgacon_text_force())
 			nouveau_modeset = 0;
-		else
 #endif
-			nouveau_modeset = 1;
 	}
 
 	if (!nouveau_modeset)

drivers/gpu/drm/nouveau/nouveau_state.c

@@ -50,6 +50,7 @@ static int nouveau_init_engine_ptrs(struct drm_device *dev)
 {
 	struct drm_nouveau_private *dev_priv = dev->dev_private;
 	struct nouveau_engine *engine = &dev_priv->engine;
+	u32 pclass = dev->pdev->class >> 8;
 
 	switch (dev_priv->chipset & 0xf0) {
 	case 0x00:
@@ -428,7 +429,8 @@ static int nouveau_init_engine_ptrs(struct drm_device *dev)
 	}
 
 	/* headless mode */
-	if (nouveau_modeset == 2) {
+	if (nouveau_modeset == 2 ||
+	    (nouveau_modeset < 0 && pclass != PCI_CLASS_DISPLAY_VGA)) {
 		engine->display.early_init = nouveau_stub_init;
 		engine->display.late_takedown = nouveau_stub_takedown;
 		engine->display.create = nouveau_stub_init;