From 9c70e93d3486eb615bb76e2658abde36a09e9d41 Mon Sep 17 00:00:00 2001
From: Thomas Zimmermann <tzimmermann@suse.de>
Date: Tue, 25 Feb 2025 22:59:22 +0900
Subject: [PATCH] drm/xe: Support 'nomodeset' kernel command-line option

BugLink: https://bugs.launchpad.net/bugs/2099996

commit 014125c64d09e58e90dde49fbb57d802a13e2559 upstream.

Setting 'nomodeset' on the kernel command line disables all graphics
drivers with modesetting capabilities, leaving only firmware drivers,
such as simpledrm or efifb.

Most DRM drivers automatically support 'nomodeset' via DRM's module
helper macros. In xe, which uses regular module_init(), manually call
drm_firmware_drivers_only() to test for 'nomodeset'. Do not register
the driver if set.

v2:
- use xe's init table (Lucas)
- do NULL test for init/exit functions

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240827121003.97429-1-tzimmermann@suse.de
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
---
 drivers/gpu/drm/xe/xe_module.c | 39 +++++++++++++++++++++++++++++++---
 1 file changed, 36 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_module.c b/drivers/gpu/drm/xe/xe_module.c
index 110b69864656..35aaf7ee76b5 100644
--- a/drivers/gpu/drm/xe/xe_module.c
+++ b/drivers/gpu/drm/xe/xe_module.c
@@ -8,6 +8,8 @@
 #include <linux/init.h>
 #include <linux/module.h>
 
+#include <drm/drm_module.h>
+
 #include "xe_drv.h"
 #include "xe_hw_fence.h"
 #include "xe_pci.h"
@@ -48,12 +50,23 @@ module_param_named_unsafe(force_probe, xe_modparam.force_probe, charp, 0400);
 MODULE_PARM_DESC(force_probe,
 		 "Force probe options for specified devices. See CONFIG_DRM_XE_FORCE_PROBE for details.");
 
+static int xe_check_nomodeset(void)
+{
+	if (drm_firmware_drivers_only())
+		return -ENODEV;
+
+	return 0;
+}
+
 struct init_funcs {
 	int (*init)(void);
 	void (*exit)(void);
 };
 
 static const struct init_funcs init_funcs[] = {
+	{
+		.init = xe_check_nomodeset,
+	},
 	{
 		.init = xe_hw_fence_module_init,
 		.exit = xe_hw_fence_module_exit,
@@ -68,15 +81,35 @@ static const struct init_funcs init_funcs[] = {
 	},
 };
 
+static int __init xe_call_init_func(unsigned int i)
+{
+	if (WARN_ON(i >= ARRAY_SIZE(init_funcs)))
+		return 0;
+	if (!init_funcs[i].init)
+		return 0;
+
+	return init_funcs[i].init();
+}
+
+static void xe_call_exit_func(unsigned int i)
+{
+	if (WARN_ON(i >= ARRAY_SIZE(init_funcs)))
+		return;
+	if (!init_funcs[i].exit)
+		return;
+
+	init_funcs[i].exit();
+}
+
 static int __init xe_init(void)
 {
 	int err, i;
 
 	for (i = 0; i < ARRAY_SIZE(init_funcs); i++) {
-		err = init_funcs[i].init();
+		err = xe_call_init_func(i);
 		if (err) {
 			while (i--)
-				init_funcs[i].exit();
+				xe_call_exit_func(i);
 			return err;
 		}
 	}
@@ -89,7 +122,7 @@ static void __exit xe_exit(void)
 	int i;
 
 	for (i = ARRAY_SIZE(init_funcs) - 1; i >= 0; i--)
-		init_funcs[i].exit();
+		xe_call_exit_func(i);
 }
 
 module_init(xe_init);