drm: Move nomodeset kernel parameter to drivers/video

Move the nomodeset kernel parameter to drivers/video to make it
available to non-DRM drivers. Adapt the interface, but keep the DRM
interface drm_firmware_drivers_only() to avoid churn within DRM. The
function should later be inlined into callers.

The parameter disables any DRM graphics driver that would replace a
driver for firmware-provided scanout buffers. It is an option to easily
fallback to basic graphics output if the hardware's native driver is
broken. Moving it to a more prominent location wil make it available
to fbdev as well.

v2:
	* clarify the meaning of the nomodeset parameter (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221111133024.9897-2-tzimmermann@suse.de

5 files changed, 13 insertions, 12 deletions

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 34f5a092c99e..722ded626399 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -8,7 +8,6 @@
 menuconfig DRM
 	tristate "Direct Rendering Manager (XFree86 4.1.0 and higher DRI support)"
 	depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && HAS_DMA
-	select DRM_NOMODESET
 	select DRM_PANEL_ORIENTATION_QUIRKS
 	select HDMI
 	select FB_CMDLINE
@@ -19,6 +18,7 @@ menuconfig DRM
 # gallium uses SYS_kcmp for os_same_file_description() to de-duplicate
 # device and dmabuf fd. Let's make sure that is available for our userspace.
 	select KCMP
+	select VIDEO_NOMODESET
 	help
 	  Kernel-level support for the Direct Rendering Infrastructure (DRI)
 	  introduced in XFree86 4.0. If you say Y here, you need to select
@@ -514,11 +514,6 @@ config DRM_EXPORT_FOR_TESTS
 config DRM_PANEL_ORIENTATION_QUIRKS
 	tristate
 
-# Separate option because nomodeset parameter is global and expected built-in
-config DRM_NOMODESET
-	bool
-	default n
-
 config DRM_LIB_RANDOM
 	bool
 	default n
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index c44a54cadb61..f92cd7892711 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -72,7 +72,6 @@ drm-$(CONFIG_DRM_PRIVACY_SCREEN) += \
 	drm_privacy_screen_x86.o
 obj-$(CONFIG_DRM)	+= drm.o
 
-obj-$(CONFIG_DRM_NOMODESET) += drm_nomodeset.o
 obj-$(CONFIG_DRM_PANEL_ORIENTATION_QUIRKS) += drm_panel_orientation_quirks.o
 
 #
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 0587e21abad9..6d2fde6c5d11 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -11,6 +11,10 @@ config APERTURE_HELPERS
 	  Support tracking and hand-over of aperture ownership. Required
 	  by graphics drivers for firmware-provided framebuffers.
 
+config VIDEO_NOMODESET
+	bool
+	default n
+
 if HAS_IOMEM
 
 config HAVE_FB_ATMEL
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index 5bb6b452cc83..a50eb528ed3c 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -2,6 +2,7 @@
 
 obj-$(CONFIG_APERTURE_HELPERS)    += aperture.o
 obj-$(CONFIG_VGASTATE)            += vgastate.o
+obj-$(CONFIG_VIDEO_NOMODESET)     += nomodeset.o
 obj-$(CONFIG_HDMI)                += hdmi.o
 
 obj-$(CONFIG_VT)		  += console/
diff --git a/drivers/gpu/drm/drm_nomodeset.c b/drivers/video/nomodeset.c
index f3978d5bd3a1..13cc8b719697 100644
--- a/drivers/gpu/drm/drm_nomodeset.c
+++ b/drivers/video/nomodeset.c
@@ -3,17 +3,19 @@
 #include <linux/module.h>
 #include <linux/types.h>
 
-static bool drm_nomodeset;
+#include <video/nomodeset.h>
 
-bool drm_firmware_drivers_only(void)
+static bool video_nomodeset;
+
+bool video_firmware_drivers_only(void)
 {
-	return drm_nomodeset;
+	return video_nomodeset;
 }
-EXPORT_SYMBOL(drm_firmware_drivers_only);
+EXPORT_SYMBOL(video_firmware_drivers_only);
 
 static int __init disable_modeset(char *str)
 {
-	drm_nomodeset = true;
+	video_nomodeset = true;
 
 	pr_warn("Booted with the nomodeset parameter. Only the system framebuffer will be available\n");