[v4,4/5] fbdev: Split frame buffer support in FB and FB_CORE symbols
Commit Message
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: Javier Martinez Canillas <javierm@redhat.com>
---
Changes in v4:
- Fix menuconfig hierarchy that was broken in v3 (Arnd Bergmann).
Changes in v3:
- Really make a hidden symbol by removing the prompt (Arnd Bergmann).
- Change FB_CORE to config instead of menuconfig (Arnd Bergmann).
- Keep "depends on FB" for FIRMWARE_EDID (Arnd Bergmann).
- Compile out fb_backlight.o and fbmon.o that are only needed for FB
(Arnd Bergmann).
- Make FB_DEVICE to depend on FB_CORE instead of selecting it.
Changes in v2:
- Keep "depends on FB" for FB_DDC, FB_HECUBA, FB_SVGALIB, FB_MACMODES,
FB_BACKLIGHT, FB_MODE_HELPERS and FB_TILEBLITTING (Arnd Bergmann).
- Don't change the fb.o object name (Arnd Bergmann).
- Make FB_CORE a non-visible Kconfig symbol instead (Thomas Zimmermann).
arch/x86/Makefile | 2 +-
arch/x86/video/Makefile | 2 +-
drivers/video/console/Kconfig | 2 +-
drivers/video/fbdev/Kconfig | 10 ++++++++--
drivers/video/fbdev/core/Kconfig | 30 +++++++++++++++++-------------
drivers/video/fbdev/core/Makefile | 8 ++++----
6 files changed, 32 insertions(+), 22 deletions(-)
Comments
On Tue, Jul 04, 2023 at 01:05:28AM +0200, Javier Martinez Canillas wrote:
> 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.
...
Wondering if
if FB_CORE
...
endif
makes Kconfig looking better instead of replacing all these "depends on" lines.
> config FB_DEVICE
> bool "Provide legacy /dev/fb* device"
> - depends on FB
> + depends on FB_CORE
> default y
On Tue, Jul 04, 2023 at 10:20:35AM +0300, Andy Shevchenko wrote:
> On Tue, Jul 04, 2023 at 01:05:28AM +0200, Javier Martinez Canillas wrote:
...
> Wondering if
>
> if FB_CORE
> ...
> endif
>
> makes Kconfig looking better instead of replacing all these "depends on" lines.
I meant user visible effect (via `make *config` and in the source code.
> > config FB_DEVICE
> > bool "Provide legacy /dev/fb* device"
> > - depends on FB
> > + depends on FB_CORE
> > default y
Hello Andy,
Andy Shevchenko <andriy.shevchenko@linux.intel.com> writes:
> On Tue, Jul 04, 2023 at 01:05:28AM +0200, Javier Martinez Canillas wrote:
>> 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.
>
> ...
>
> Wondering if
>
> if FB_CORE
> ...
> endif
>
> makes Kconfig looking better instead of replacing all these "depends on" lines.
>
Yes, I discussed that with Arnd and he said that the if / endif is just
syntax sugar so I didn't do that change to keep the patches simpler. But
is something that you could change as a follow-up if you prefer that way.
@@ -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
@@ -1,2 +1,2 @@
# SPDX-License-Identifier: GPL-2.0-only
-obj-$(CONFIG_FB) += fbdev.o
+obj-$(CONFIG_FB_CORE) += fbdev.o
@@ -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
@@ -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.
@@ -3,6 +3,10 @@
# fbdev core configuration
#
+config FB_CORE
+ select VIDEO_CMDLINE
+ tristate
+
config FB_NOTIFY
bool
@@ -23,7 +27,7 @@ config FIRMWARE_EDID
config FB_DEVICE
bool "Provide legacy /dev/fb* device"
- depends on FB
+ depends on FB_CORE
default y
help
Say Y here if you want the legacy /dev/fb* device file and
@@ -39,7 +43,7 @@ config FB_DDC
config FB_CFB_FILLRECT
tristate
- depends on FB
+ depends on FB_CORE
help
Include the cfb_fillrect function for generic software rectangle
filling. This is used by drivers that don't provide their own
@@ -47,7 +51,7 @@ config FB_CFB_FILLRECT
config FB_CFB_COPYAREA
tristate
- depends on FB
+ depends on FB_CORE
help
Include the cfb_copyarea function for generic software area copying.
This is used by drivers that don't provide their own (accelerated)
@@ -55,7 +59,7 @@ config FB_CFB_COPYAREA
config FB_CFB_IMAGEBLIT
tristate
- depends on FB
+ depends on FB_CORE
help
Include the cfb_imageblit function for generic software image
blitting. This is used by drivers that don't provide their own
@@ -63,7 +67,7 @@ config FB_CFB_IMAGEBLIT
config FB_CFB_REV_PIXELS_IN_BYTE
bool
- depends on FB
+ depends on FB_CORE
help
Allow generic frame-buffer functions to work on displays with 1, 2
and 4 bits per pixel depths which has opposite order of pixels in
@@ -71,7 +75,7 @@ config FB_CFB_REV_PIXELS_IN_BYTE
config FB_SYS_FILLRECT
tristate
- depends on FB
+ depends on FB_CORE
help
Include the sys_fillrect function for generic software rectangle
filling. This is used by drivers that don't provide their own
@@ -79,7 +83,7 @@ config FB_SYS_FILLRECT
config FB_SYS_COPYAREA
tristate
- depends on FB
+ depends on FB_CORE
help
Include the sys_copyarea function for generic software area copying.
This is used by drivers that don't provide their own (accelerated)
@@ -87,7 +91,7 @@ config FB_SYS_COPYAREA
config FB_SYS_IMAGEBLIT
tristate
- depends on FB
+ depends on FB_CORE
help
Include the sys_imageblit function for generic software image
blitting. This is used by drivers that don't provide their own
@@ -126,22 +130,22 @@ endchoice
config FB_SYS_FOPS
tristate
- depends on FB
+ depends on FB_CORE
config FB_DEFERRED_IO
bool
- depends on FB
+ depends on FB_CORE
config FB_IO_HELPERS
bool
- depends on FB
+ depends on FB_CORE
select FB_CFB_COPYAREA
select FB_CFB_FILLRECT
select FB_CFB_IMAGEBLIT
config FB_SYS_HELPERS
bool
- depends on FB
+ depends on FB_CORE
select FB_SYS_COPYAREA
select FB_SYS_FILLRECT
select FB_SYS_FOPS
@@ -149,7 +153,7 @@ config FB_SYS_HELPERS
config FB_SYS_HELPERS_DEFERRED
bool
- depends on FB
+ depends on FB_CORE
select FB_DEFERRED_IO
select FB_SYS_HELPERS
@@ -1,10 +1,10 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_FB_NOTIFY) += fb_notify.o
-obj-$(CONFIG_FB) += fb.o
-fb-y := fb_backlight.o \
- fb_info.o \
- fbmem.o fbmon.o fbcmap.o \
+obj-$(CONFIG_FB_CORE) += fb.o
+fb-y := fb_info.o \
+ fbmem.o fbcmap.o \
modedb.o fbcvt.o fb_cmdline.o fb_io_fops.o
+fb-$(CONFIG_FB) += fb_backlight.o fbmon.o
fb-$(CONFIG_FB_DEFERRED_IO) += fb_defio.o
fb-$(CONFIG_FB_DEVICE) += fb_chrdev.o \
fb_procfs.o \