Unverified Commit 55bffc81 authored by Javier Martinez Canillas's avatar Javier Martinez Canillas
Browse files

fbdev: Split frame buffer support in FB and FB_CORE symbols 



Currently the CONFIG_FB option has to be enabled even if no legacy fbdev
drivers are needed (e.g: only to have support for framebuffer consoles).

The DRM subsystem has a fbdev emulation layer, but depends on CONFIG_FB
and so it can only be enabled if that dependency is enabled as well.

That means fbdev drivers have to be explicitly disabled if users want to
enable CONFIG_FB, only to use fbcon and/or the DRM fbdev emulation layer.

This patch introduces a non-visible CONFIG_FB_CORE symbol that could be
enabled just to have core support needed for CONFIG_DRM_FBDEV_EMULATION,
allowing CONFIG_FB to be disabled (and automatically disabling all the
fbdev drivers).

Nothing from fb_backlight.o and fbmon.o is used by the DRM fbdev emulation
layer so these two objects can be compiled out when CONFIG_FB is disabled.

Signed-off-by: default avatarJavier Martinez Canillas <javierm@redhat.com>
Reviewed-by: default avatarArnd Bergmann <arnd@arndb.de>
Tested-by: default avatarArnd Bergmann <arnd@arndb.de>
Acked-by: default avatarHelge Deller <deller@gmx.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20230719081544.741051-4-javierm@redhat.com
parent df791524

arch/x86/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -259,7 +259,7 @@ drivers-$(CONFIG_PCI) += arch/x86/pci/ 
# suspend and hibernation support

drivers-$(CONFIG_PM) += arch/x86/power/



drivers-$(CONFIG_FB) += arch/x86/video/

drivers-$(CONFIG_FB_CORE) += arch/x86/video/



####

# boot loader support. Several targets are kept for legacy purposes

arch/x86/video/Makefile

+1 −1
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0-only

obj-$(CONFIG_FB)               += fbdev.o
 
obj-$(CONFIG_FB_CORE)		+= fbdev.o

drivers/video/backlight/backlight.c

+3 −3
Original line number Diff line number Diff line
@@ -79,7 +79,7 @@ static const char *const backlight_scale_types[] = { 
	[BACKLIGHT_SCALE_NON_LINEAR]	= "non-linear",

};



#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \

#if defined(CONFIG_FB_CORE) || (defined(CONFIG_FB_CORE_MODULE) && \

				defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))

/*

 * fb_notifier_callback
@@ -155,7 +155,7 @@ static inline int backlight_register_fb(struct backlight_device *bd) 
static inline void backlight_unregister_fb(struct backlight_device *bd)

{

}

#endif /* CONFIG_FB */

#endif /* CONFIG_FB_CORE */



static void backlight_generate_event(struct backlight_device *bd,

				     enum backlight_update_reason reason)

drivers/video/console/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -72,7 +72,7 @@ config DUMMY_CONSOLE_ROWS 


config FRAMEBUFFER_CONSOLE

	bool "Framebuffer Console support"

	depends on FB && !UML

	depends on FB_CORE && !UML

	select VT_HW_CONSOLE_BINDING

	select CRC32

	select FONT_SUPPORT

drivers/video/fbdev/Kconfig

+8 −2
Original line number Diff line number Diff line
@@ -4,9 +4,9 @@ 
#



menuconfig FB

	tristate "Support for frame buffer devices"

	tristate "Support for frame buffer device drivers"

	select FB_CORE

	select FB_NOTIFY

	select VIDEO_CMDLINE

	help

	  The frame buffer device provides an abstraction for the graphics

	  hardware. It represents the frame buffer of some video hardware and
@@ -30,6 +30,12 @@ menuconfig FB 
	  <http://www.munted.org.uk/programming/Framebuffer-HOWTO-1.3.html> for more

	  information.



	  This enables support for native frame buffer device (fbdev) drivers.



	  The DRM subsystem provides support for emulated frame buffer devices

	  on top of KMS drivers, but this option allows legacy fbdev drivers to

	  be enabled as well.



	  Say Y here and to the driver for your graphics board below if you

	  are compiling a kernel for a non-x86 architecture.