The /sys/class/backlight (drivers/video/backlight/apple_bl.c)
functionality on my Apple "MacBook2,1" no longer works. It did work
before my harddrive crashed but I no longer have those kernel .config
files, but I'm beginning to think the problem might not be with my
configuration. A notable difference with the way I'm running the laptop
now is that I no longer boot "normally" off an internal sata harddrive,
but rather using the alternative method (pressing the on button while
holding down the Alt key) which allows me to boot off a usb stick --
which, I think (not sure), involves a lot more EFI stuff.
I tried testing with kernels ranging from the most recent stable
4.15.7, 4.10, 4.8 and 4.7, and all basically behave the same way -- an
empty /sys/class/backlight directory, and no errors in dmesg, nor when
I load apple_bl as a module.
I tried playing with various kernel command line parameters, like
acpi_backlight=vendor|video|native, video.use_native_backlight=1,
acpi_osi=, etc, with no effect.
# find /sys | grep -i backl
/sys/class/backlight
/sys/bus/acpi/drivers/Apple backlight
/sys/bus/acpi/drivers/Apple backlight/bind
/sys/bus/acpi/drivers/Apple backlight/unbind
/sys/bus/acpi/drivers/Apple backlight/uevent
/sys/module/video/parameters/disable_backlight_sysfs_if
# cat /sys/module/video/parameters/disable_backlight_sysfs_if
-1
# find /sys | grep -i apple | grep -v applesmc | grep
# -v /sys/firmware/efi
/sys/bus/hid/drivers/apple
/sys/bus/hid/drivers/apple/bind
/sys/bus/hid/drivers/apple/0003:05AC:021A.0001
/sys/bus/hid/drivers/apple/unbind
/sys/bus/hid/drivers/apple/module
/sys/bus/hid/drivers/apple/0003:05AC:021A.0002
/sys/bus/hid/drivers/apple/uevent
/sys/bus/hid/drivers/apple/new_id
/sys/bus/acpi/drivers/Apple backlight
/sys/bus/acpi/drivers/Apple backlight/bind
/sys/bus/acpi/drivers/Apple backlight/unbind
/sys/bus/acpi/drivers/Apple backlight/uevent
/sys/module/apple_bl
/sys/module/apple_bl/parameters
/sys/module/apple_bl/parameters/debug
/sys/module/apple_bl/uevent
/sys/module/hid_apple
/sys/module/hid_apple/parameters
/sys/module/hid_apple/parameters/ejectcd_as_delete
/sys/module/hid_apple/parameters/iso_layout
/sys/module/hid_apple/parameters/rightalt_as_rightctrl
/sys/module/hid_apple/parameters/swap_opt_cmd
/sys/module/hid_apple/parameters/fnmode
/sys/module/hid_apple/parameters/swap_fn_leftctrl
/sys/module/hid_apple/uevent
/sys/module/hid_apple/drivers
/sys/module/hid_apple/drivers/hid:apple
# cat .config | grep APPLE | grep -v ^#
CONFIG_SENSORS_APPLESMC=y
CONFIG_BACKLIGHT_APPLE=y
CONFIG_HID_APPLE=y
CONFIG_APPLE_GMUX=m
CONFIG_APPLE_PROPERTIES=y
# cat .config | grep BACKLIGHT | grep -v ^#
CONFIG_BACKLIGHT_LCD_SUPPORT=y
CONFIG_BACKLIGHT_CLASS_DEVICE=y
CONFIG_BACKLIGHT_APPLE=y
# cat .config | grep FB | grep -v ^#
CONFIG_FB=y
CONFIG_FB_CMDLINE=y
CONFIG_FB_NOTIFY=y
CONFIG_FB_CFB_FILLRECT=y
CONFIG_FB_CFB_COPYAREA=y
CONFIG_FB_CFB_IMAGEBLIT=y
CONFIG_FB_MODE_HELPERS=y
CONFIG_FB_TILEBLITTING=y
CONFIG_FB_EFI=y
# cat .config| grep EFI | grep -v ^#
CONFIG_EFI=y
CONFIG_EFI_STUB=y
CONFIG_EFI_MIXED=y
CONFIG_FB_EFI=y
CONFIG_DMI_SCAN_MACHINE_NON_EFI_FALLBACK=y
CONFIG_EFI_VARS=y
CONFIG_EFI_ESRT=y
CONFIG_EFI_RUNTIME_MAP=y
CONFIG_EFI_RUNTIME_WRAPPERS=y
CONFIG_EFI_DEV_PATH_PARSER=y
CONFIG_EFIVAR_FS=y
CONFIG_EARLY_PRINTK_EFI=y
# dmesg | grep -i apple
[ 0.000000] Command line: BOOT_IMAGE=/efi/boot/linux root=/dev/sdb1
rootwait apple_bl.debug=1 [ 0.000000] efi: EFI v1.10 by Apple
[ 0.000000] DMI: Apple Inc. MacBook2,1/Mac-F4208CAA, BIOS
MB21.88Z.00A5.B07.0706270922 06/27/07 [ 0.000000] ACPI: RSDP
0x000000003EEFD014 000024 (v02 APPLE ) [ 0.000000] ACPI: XSDT
0x000000003EEFD1C0 00006C (v01 APPLE Apple00 000000A5 01000013)
[ 0.000000] ACPI: FACP 0x000000003EEFB000 0000F4 (v03 APPLE
Apple00 000000A5 Loki 0000005F) [ 0.000000] ACPI: DSDT
0x000000003EEF0000 0041E4 (v01 APPLE MacBook 00020001 INTL 20050309)
[ 0.000000] ACPI: HPET 0x000000003EEFA000 000038 (v01 APPLE
Apple00 00000001 Loki 0000005F) [ 0.000000] ACPI: APIC
0x000000003EEF9000 000068 (v01 APPLE Apple00 00000001 Loki 0000005F)
[ 0.000000] ACPI: MCFG 0x000000003EEF8000 00003C (v01 APPLE
Apple00 00000001 Loki 0000005F) [ 0.000000] ACPI: ASF!
0x000000003EEF7000 0000A0 (v32 APPLE Apple00 00000001 Loki 0000005F)
[ 0.000000] ACPI: SBST 0x000000003EEF6000 000030 (v01 APPLE
Apple00 00000001 Loki 0000005F) [ 0.000000] ACPI: ECDT
0x000000003EEF5000 000053 (v01 APPLE Apple00 00000001 Loki 0000005F)
[ 0.000000] ACPI: SSDT 0x000000003EEB9000 0001DA (v01 APPLE
SataAhci 00001000 INTL 20050309) [ 0.000000] ACPI: SSDT
0x000000003EEEF000 0004DC (v01 APPLE CpuPm 00003000 INTL 20050309)
[ 0.000000] ACPI: DMI detected to setup _OSI("Darwin"): Apple
hardware [ 0.000000] Kernel command line: BOOT_IMAGE=/efi/boot/linux
root=/dev/sdb1 rootwait apple_bl.debug=1 [ 0.094230] ACPI: SSDT
0xFFFFA1DF7EB52C00 0002AE (v01 APPLE Cpu0Ist 00003000 INTL 20050309)
[ 0.094230] ACPI: SSDT 0xFFFFA1DF7EB53000 0002A0 (v01 APPLE
Cpu0Cst 00003001 INTL 20050309) [ 0.094230] ACPI: SSDT
0xFFFFA1DF7EA78240 000087 (v01 APPLE Cpu1Ist 00003000 INTL 20050309)
[ 0.094230] ACPI: SSDT 0xFFFFA1DF7EA78300 000085 (v01 APPLE
Cpu1Cst 00003000 INTL 20050309) [ 0.574790] applesmc: key=226 fan=1
temp=10 index=10 acc=1 lux=0 kbd=0 [ 0.648841] input: applesmc
as /devices/platform/applesmc.768/input/input5 [ 0.650244] applesmc
applesmc.768: hwmon_device_register() is deprecated. Please convert the
driver to use hwmon_device_register_with_info(). [ 1.817401] usb
2-2: Product: Apple Internal Keyboard / Trackpad [ 1.818999] usb
2-2: Manufacturer: Apple Computer [ 1.830534] input: Apple Computer
Apple Internal Keyboard / Trackpad
as /devices/pci0000:00/0000:00:1d.0/usb2/2-2/2-2:1.0/0003:05AC:021A.0001/input/input6
[ 1.910299] apple 0003:05AC:021A.0001: input,hidraw0: USB HID v1.11
Keyboard [Apple Computer Apple Internal Keyboard / Trackpad] on
usb-0000:00:1d.0-2/input0 [ 1.918387] input: Apple Computer Apple
Internal Keyboard / Trackpad
as /devices/pci0000:00/0000:00:1d.0/usb2/2-2/2-2:1.2/0003:05AC:021A.0002/input/input7
[ 1.990288] apple 0003:05AC:021A.0002: input,hidraw1: USB HID v1.11
Device [Apple Computer Apple Internal Keyboard / Trackpad] on
usb-0000:00:1d.0-2/input2 [ 3.480436] usb 4-2: Manufacturer: Apple
Computer, Inc. [ 3.488709] hid-generic 0003:05AC:8240.0003:
hiddev96,hidraw2: USB HID v1.11 Device [Apple Computer, Inc. IR
Receiver] on usb-0000:00:1d.2-2/input0
# dmesg | grep -i fb
[ 0.000000] ACPI: FACP 0x000000003EEFB000 0000F4 (v03 APPLE
Apple00 000000A5 Loki 0000005F) [ 0.110099] pci 0000:00:02.0: BAR
2: assigned to efifb [ 0.111406] pci 0000:00:1f.3: reg 0x20: [io
0xefa0-0xefbf] [ 0.220957] efifb: dmi detected MacBook2,1 -
framebuffer at 0x40000000 (1280x800, stride 8192) [ 0.227731] efifb:
probing for efifb [ 0.227746] efifb: framebuffer at 0x40000000,
using 6400k, total 6400k [ 0.227750] efifb: mode is 1280x800x32,
linelength=8192, pages=1 [ 0.227753] efifb: scrolling: redraw
[ 0.227757] efifb: Truecolor: size=8:8:8:8, shift=24:16:8:0
[ 0.234203] fb0: EFI VGA frame buffer device
# dmesg | grep -i osi
[ 0.000000] ACPI: DMI detected to setup _OSI("Darwin"): Apple
hardware [ 0.094230] ACPI: Disabled all _OSI OS vendors
[ 0.094230] ACPI: Added _OSI(Module Device)
[ 0.094230] ACPI: Added _OSI(Processor Device)
[ 0.094230] ACPI: Added _OSI(3.0 _SCP Extensions)
[ 0.094230] ACPI: Added _OSI(Processor Aggregator Device)
[ 0.094230] ACPI: Added _OSI(Darwin)
[ 0.094230] ACPI: BIOS _OSI(Darwin) query honored via DMI
