[i915][kms] kernel backlight interface missing for macbooks

Here is a patch for MacBook1,1.

This method should work for all intel macbooks.
If you patch xserver-xorg-video-intel like in bug #417770
the brightness hotkeys work again.

This modification indeed makes mpb_backlight module available in /sys/class/backlight, modifying brightness works as promised. This is on macbook 3.1.

@sroecker, I cannot see this patch upstream in Linus tree. Have you submitted it upstream ? If not, can you submit the patch upstream. Here is a link which tells you about the procedure to do so, in case you need it:
https://wiki.ubuntu.com/KernelTeam/KernelPatches.

Did you cherry-pick 36bc5ee6a8d13333980fa54e97d3469d3d4cda98 ?
You should include http://lkml.org/lkml/2010/3/23/412 which fixes this for MacBook1,1.

This bug was fixed in the package linux - 2.6.32-19.28

---------------
linux (2.6.32-19.28) lucid; urgency=low

  [ Andy Whitcroft ]

  * [Config] enable various multitouch devices
    - LP: #541453

  [ Chase Douglas ]

  * (pre-stable): input: ALPS - Add signature for HP Pavilion dm3 laptops
    - LP: #545307
  * SAUCE: Disable function tracing after hitting __schedule_bug
  * SAUCE: Reduce ACPI resource conflict message to KERN_INFO, printf
    cleanup
    - LP: #440470

  [ Jesse Barnes ]

  * SAUCE: drm/i915: don't change DRM configuration when releasing load
    detect pipe
    - LP: #488328

  [ John Johansen ]

  * SAUCE: AppArmor: Remove null_profile's use of PFLAG_NO_LIST_REF
    - LP: #539437
  * SAUCE: AppArmor: Stop page allocation warnings that can occur on policy
    load
    - LP: #458299
  * SAUCE: AppArmor: Return string len rather than the allocation size
    - LP: #551844
  * SAUCE: AppArmor: Fix oops in profile verification if profile unpack
    fails.

  [ Luke Yelavich ]

  * [Config] Enable Nouveau DRM module on powerpc

  [ Stefan Bader ]

  * SAUCE: Pull in thinkpad-acpi from v2.6.34-rc1
    - LP: #357673
  * [Config] Enable thinkpad-acpi ALSA volume control
    - LP: #357673

  [ Steve Conklin ]

  * SAUCE: drm/i915: Disable FBC on 915GM and 945GM
    - LP: #492392, #539609

  [ Upstream Kernel Changes ]

  * Revert "(pre-stable) drm/i915: blacklist lid status: Sony VGN-BX196VP,
    Dell Inspiron 700m"
    - LP: #515246
  * (pre-stable) softlockup: Stop spurious softlockup messages due to
    overflow
    - LP: #551068
  * backlight: mbp_nvidia_bl - add five more MacBook variants
    - LP: #511965
  * drm/nv04-nv40: Fix up the programmed horizontal sync pulse delay.
    - LP: #529130
  * drm/nouveau: Fix fbcon corruption with font width not divisible by 8
    - LP: #544739
  * (pre-stable) USB: fix usbfs regression
  * drm/radeon/bo: add some fallback placements for VRAM only objects.
    - LP: #507148
  * drm/radeon/kms: don't print error on -ERESTARTSYS.
    - LP: #507148
  * Input: add the ABS_MT_PRESSURE event
    - LP: #541453
  * HID: Support for 3M multitouch panel
    - LP: #541453
  * HID: make 3M PCT touchscreen driver standalone config option
    - LP: #541453
  * HID: add support for Stantum multitouch panel
    - LP: #541453
  * HID: make Stantum driver standalone config option
    - LP: #541453
  * HID: add support for Acer T230H multitouch
    - LP: #541453
  * HID: add support for Pixart Imaging Optical Touch Screen
    - LP: #541453
  * HID: fixed bug in single-touch emulation on the stantum panel
    - LP: #541453
  * HID: add pressure support for the Stantum multitouch panel
    - LP: #541453
  * HID: Support for MosArt multitouch panel
    - LP: #541453
  * HID: hid-ntrig add multi input quirk and clean up
    - LP: #541453
  * HID: n-trig: remove unnecessary tool switching
    - LP: #541453
  * HID: hid-ntrig: multitouch cleanup and fix
    - LP: #541453
  * HID: hid-ntrig: Single touch mode tap
    - LP: #541453
  * hid: ntrig touch events
    - LP: #541453
  * (pre-stable) x86-32, resume: do a global tlb flush in S4 resume
    - LP: #531309
  * drm/i915: Part of: Add initial bits for VGA mode...

Not working with MacBook1,1 , MacBook Pro 1,1 and potentially other MacBooks not in the kernel module. (see bug 397617)

As asked in bug 397617:

$ sudo dmidecode -s system-manufacturer
Apple Computer, Inc.
$ sudo dmidecode -s system-product-name
MacBook1,1
$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03)

Requested information from bug 397617:

$ sudo dmidecode -s system-manufacturer
Apple Computer, Inc.
$ sudo dmidecode -s system-product-name
MacBookPro1,1
$ lspci | grep VGA
01:00.0 VGA compatible controller: ATI Technologies Inc M56P [Radeon Mobility X1600]

I confirm patch patch mentioned in comment #5 works wonderfully in my Macbook1,1 (first gen white macbook).
That patch is not included in latest kernel (linux-image-2.6.32-21-generic 2.6.32-21.32).

$ sudo dmidecode -s system-manufacturer
Apple Computer, Inc.
$ sudo dmidecode -s system-product-name
MacBook1,1
$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03)

How to test:
$ sudo apt-get install linux-source
$ cd /tmp/ && tar xvfj /usr/src/linux-source* && cd linux-source-*
<< apply patch here to drivers/video/backlight/mbp_nvidia_bl.c >>
$ make oldconfig && make prepare && make scripts
$ cp /lib/modules/$(uname -r)/build/Module.symvers .
$ make M=drivers/video/backlight
$ sudo insmod drivers/video/backlight/mbp_nvidia_bl.ko
<< restart X, F1/F2 controls should be working >>

Thanks Aldrin, I can confirm the instructions in comment #10 for applying the patch in comment #5 work flawlessly on my MacBook 1,1

As an appendix to the instructions posted by Aldrin in comment #11, if you want to install the module in a more permanent way, replace the last step (sudo insmod ...) by this:
$ uname -r > include/config/kernel.release
$ sudo make M=drivers/video/backlight modules_install

I forgot a step in my previous post:
$ sudo depmod -a

adding the below to my drivers/video/backlight/mbp_nvidia_bl.c fixed the problem for me on my MacBookPro1,1 after recompiling and inserting the module

 {
  .callback = mbp_dmi_match,
  .ident = "MacBookPro 1,1",
  .matches = {
   DMI_MATCH(DMI_SYS_VENDOR, "Apple Computer, Inc."),
   DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro1,1"),
  },
  .driver_data = (void *)&intel_chipset_data,
 },

The code Eric mentions in comment 14 has been added in the upstream kernel tree, along with similar code for other MacBookPro's, and will hopefully be included in kernel 2.6.35.

This bug report was marked as Incomplete and has not had any updated comments for quite some time. As a result this bug is being closed. Please reopen if this is still an issue in the current Ubuntu release http://www.ubuntu.com/getubuntu/download . Also, please be sure to provide any requested information that may have been missing. To reopen the bug, click on the current status under the Status column and change the status back to "New". Thanks.

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