From 8ec434086c84ba677eb698085612162ea6287249 Mon Sep 17 00:00:00 2001
From: Javier Martinez Canillas <javierm@redhat.com>
Date: Fri, 17 Dec 2021 01:37:52 +0100
Subject: drm/xen: Add support for the nomodeset kernel parameter
Git-commit: 9d6bf794084d9258dadf2754d911fcfeb13ea8fc
Patch-mainline: v5.18-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

According to disable Documentation/admin-guide/kernel-parameters.txt, this
parameter can be used to disable kernel modesetting.

DRM drivers will not perform display-mode changes or accelerated rendering
and only the system framebuffer will be available if it was set-up.

But only a few DRM drivers currently check for nomodeset, make this driver
to also support the command line parameter.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20211217003752.3946210-38-javierm@redhat.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/xen/xen_drm_front.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c
index e63088c2121d..0d8e6bd1ccbf 100644
--- a/drivers/gpu/drm/xen/xen_drm_front.c
+++ b/drivers/gpu/drm/xen/xen_drm_front.c
@@ -495,6 +495,9 @@ static int xen_drm_drv_init(struct xen_drm_front_info *front_info)
 	struct drm_device *drm_dev;
 	int ret;
 
+	if (drm_firmware_drivers_only())
+		return -ENODEV;
+
 	DRM_INFO("Creating %s\n", xen_drm_driver.desc);
 
 	drm_info = kzalloc(sizeof(*drm_info), GFP_KERNEL);
-- 
2.38.1