drm/radeon: restore nomodeset operation (v2)

When UMS was deprecated it removed support for nomodeset commandline
we really want this in distro land so we can debug stuff, everyone
should fallback to vesa correctly.

v2: oops -1 isn't used anymore, restore original behaviour
-1 is default, so we can boot with nomodeset on the command line,
then use radeon.modeset=1 to override it for debugging later.

Cc: stable@vger.kernel.org
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_drv.c

@@ -147,7 +147,7 @@ static inline void radeon_unregister_atpx_handler(void) {}
 #endif
 
 int radeon_no_wb;
-int radeon_modeset = 1;
+int radeon_modeset = -1;
 int radeon_dynclks = -1;
 int radeon_r4xx_atom = 0;
 int radeon_agpmode = 0;
@@ -456,6 +456,16 @@ static struct pci_driver radeon_kms_pci_driver = {
 
 static int __init radeon_init(void)
 {
+#ifdef CONFIG_VGA_CONSOLE
+	if (vgacon_text_force() && radeon_modeset == -1) {
+		DRM_INFO("VGACON disable radeon kernel modesetting.\n");
+		radeon_modeset = 0;
+	}
+#endif
+	/* set to modesetting by default if not nomodeset */
+	if (radeon_modeset == -1)
+		radeon_modeset = 1;
+
 	if (radeon_modeset == 1) {
 		DRM_INFO("radeon kernel modesetting enabled.\n");
 		driver = &kms_driver;