Bug 40455

Summary: [GM45] failure to control backlight
Product: DRI Reporter: christobzr
Component: DRM/IntelAssignee: Daniel Vetter <daniel>
Status: RESOLVED INVALID QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: major    
Priority: medium CC: alan.zimm, ben, chris, christobzr, eugeni, gentoo-bugs, jani.nikula, jbarnes
Version: XOrg git   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
Attachments:
Description Flags
xorg log
none
dmesg output (with boot option "drm.debug=0x06") none

Description christobzr 2011-08-29 04:58:45 UTC
Advanced apologies if this is the wrong place to raise this issue. I hope this report adequately illustrates the problem.

I installed a gentoo system on my new laptop, on first boot the screen is blank : the backlight is off. I can make out text with a flashlight. If I log on as root I can switch the backlight on with the command "setpci -s 00:02.0 F4.B=00" (got this tip from the net). Brightness control does not work.

I compiled kernel with i915 driver (I think : ->Device Drivers ->Graphics support ->Direct Rendering Manager -> Intel 8xx/9xx/G3x/G4x/HD Graphics), with "Enable modesetting on intel by default" activated.

I can get a display by appending "nomodeset" to the Grub boot command, I believe this precludes the use of intel drivers for X, it does not permit adequate screen resolution for terminal. Same results if I deactivate "Enable modesetting on intel by default".

I tried kernel 3.0.3 : same issue. I tried Ubuntu 11.04 and mint 11 : same issue. Debian-Mint works, didn't investigate why, but suppose older kernel version : from forum posts I understand this issue appeared with recent kernels, someone specifies 2.6.38.8 as first introducing the bug.

Googleing this issue makes me suspect that all 4500M users are concerned, and would be affected when they upgrade to newer kernels.

Forum thread where I discuss this issue (I provide more system info there [lspci, kernel config, gentoo configuration]) : http://forums.gentoo.org/viewtopic-p-6797468.html#6797468

Nice bug report for ubuntu, several people and machines affected : https://bugs.launchpad.net/ubuntu/+source/linux/+bug/752165

Kernel bug report (I'm wondering if this guy reported the issue in the wrong place) : https://bugzilla.kernel.org/show_bug.cgi?id=35072#c1

I will be happy to provide any help/further information that I can, I am on holiday at the moment, I have web access only once a week, but I will respond as soon as possible.

Thank you.


System information :
Acer Aspire 5736Z
Mobile Intel® GM45 Express chipset 
Gentoo linux
uname -r : 2.6.39-gentoo-r3
uname -m : x86_64
xf86-video-intel-2.14.0
xorg-server-1.10.2
libdrm-2.4.26
mesa-7.10.3
xorg.conf : default (none)
glxinfo : see end of post

glxinfo :
name of display: :0.0
display: :0  screen: 0
direct rendering: Yes
server glx vendor string: SGI
server glx version string: 1.4
server glx extensions:
    GLX_ARB_multisample, GLX_EXT_import_context, GLX_EXT_texture_from_pixmap, 
    GLX_EXT_visual_info, GLX_EXT_visual_rating, GLX_MESA_copy_sub_buffer, 
    GLX_OML_swap_method, GLX_SGI_make_current_read, GLX_SGI_swap_control, 
    GLX_SGIS_multisample, GLX_SGIX_fbconfig, GLX_SGIX_pbuffer, 
    GLX_SGIX_visual_select_group, GLX_INTEL_swap_event
client glx vendor string: Mesa Project and SGI
client glx version string: 1.4
client glx extensions:
    GLX_ARB_get_proc_address, GLX_ARB_multisample, GLX_EXT_import_context, 
    GLX_EXT_visual_info, GLX_EXT_visual_rating, GLX_MESA_copy_sub_buffer, 
    GLX_MESA_swap_control, GLX_OML_swap_method, GLX_OML_sync_control, 
    GLX_SGI_make_current_read, GLX_SGI_swap_control, GLX_SGI_video_sync, 
    GLX_SGIS_multisample, GLX_SGIX_fbconfig, GLX_SGIX_pbuffer, 
    GLX_SGIX_visual_select_group, GLX_EXT_texture_from_pixmap, 
    GLX_INTEL_swap_event
GLX version: 1.4
GLX extensions:
    GLX_ARB_get_proc_address, GLX_ARB_multisample, GLX_EXT_import_context, 
    GLX_EXT_visual_info, GLX_EXT_visual_rating, GLX_MESA_copy_sub_buffer, 
    GLX_MESA_swap_control, GLX_OML_swap_method, GLX_OML_sync_control, 
    GLX_SGI_make_current_read, GLX_SGI_swap_control, GLX_SGI_video_sync, 
    GLX_SGIS_multisample, GLX_SGIX_fbconfig, GLX_SGIX_pbuffer, 
    GLX_SGIX_visual_select_group, GLX_EXT_texture_from_pixmap, 
    GLX_INTEL_swap_event
OpenGL vendor string: Tungsten Graphics, Inc
OpenGL renderer string: Mesa DRI Mobile Intel�� GM45 Express Chipset  
OpenGL version string: 2.1 Mesa 7.10.3
OpenGL shading language version string: 1.20
OpenGL extensions:
    GL_ARB_copy_buffer, GL_ARB_depth_clamp, GL_ARB_depth_texture, 
    GL_ARB_draw_buffers, GL_ARB_draw_elements_base_vertex, 
    GL_ARB_explicit_attrib_location, GL_ARB_fragment_coord_conventions, 
    GL_ARB_fragment_program, GL_ARB_fragment_program_shadow, 
    GL_ARB_fragment_shader, GL_ARB_framebuffer_object, 
    GL_ARB_half_float_pixel, GL_ARB_half_float_vertex, 
    GL_ARB_map_buffer_range, GL_ARB_multisample, GL_ARB_multitexture, 
    GL_ARB_occlusion_query, GL_ARB_pixel_buffer_object, 
    GL_ARB_point_parameters, GL_ARB_point_sprite, GL_ARB_provoking_vertex, 
    GL_ARB_seamless_cube_map, GL_ARB_shader_objects, 
    GL_ARB_shading_language_100, GL_ARB_shadow, GL_ARB_sync, 
    GL_ARB_texture_border_clamp, GL_ARB_texture_compression, 
    GL_ARB_texture_cube_map, GL_ARB_texture_env_add, 
    GL_ARB_texture_env_combine, GL_ARB_texture_env_crossbar, 
    GL_ARB_texture_env_dot3, GL_ARB_texture_mirrored_repeat, 
    GL_ARB_texture_non_power_of_two, GL_ARB_texture_rectangle, 
    GL_ARB_texture_rg, GL_ARB_texture_swizzle, GL_ARB_transpose_matrix, 
    GL_ARB_vertex_array_bgra, GL_ARB_vertex_array_object, 
    GL_ARB_vertex_buffer_object, GL_ARB_vertex_program, GL_ARB_vertex_shader, 
    GL_ARB_window_pos, GL_EXT_abgr, GL_EXT_bgra, GL_EXT_blend_color, 
    GL_EXT_blend_equation_separate, GL_EXT_blend_func_separate, 
    GL_EXT_blend_logic_op, GL_EXT_blend_minmax, GL_EXT_blend_subtract, 
    GL_EXT_compiled_vertex_array, GL_EXT_copy_texture, GL_EXT_draw_buffers2, 
    GL_EXT_draw_range_elements, GL_EXT_fog_coord, GL_EXT_framebuffer_blit, 
    GL_EXT_framebuffer_multisample, GL_EXT_framebuffer_object, 
    GL_EXT_gpu_program_parameters, GL_EXT_multi_draw_arrays, 
    GL_EXT_packed_depth_stencil, GL_EXT_packed_pixels, 
    GL_EXT_pixel_buffer_object, GL_EXT_point_parameters, 
    GL_EXT_polygon_offset, GL_EXT_provoking_vertex, GL_EXT_rescale_normal, 
    GL_EXT_secondary_color, GL_EXT_separate_shader_objects, 
    GL_EXT_separate_specular_color, GL_EXT_shadow_funcs, 
    GL_EXT_stencil_two_side, GL_EXT_stencil_wrap, GL_EXT_subtexture, 
    GL_EXT_texture3D, GL_EXT_texture_cube_map, GL_EXT_texture_edge_clamp, 
    GL_EXT_texture_env_add, GL_EXT_texture_env_combine, 
    GL_EXT_texture_env_dot3, GL_EXT_texture_filter_anisotropic, 
    GL_EXT_texture_lod_bias, GL_EXT_texture_object, GL_EXT_texture, 
    GL_EXT_texture_rectangle, GL_EXT_texture_sRGB, GL_EXT_texture_swizzle, 
    GL_EXT_vertex_array_bgra, GL_EXT_vertex_array, GL_OES_EGL_image, 
    GL_OES_read_format, GL_3DFX_texture_compression_FXT1, 
    GL_APPLE_client_storage, GL_APPLE_object_purgeable, 
    GL_APPLE_packed_pixels, GL_APPLE_vertex_array_object, 
    GL_ATI_blend_equation_separate, GL_ATI_envmap_bumpmap, 
    GL_ATI_separate_stencil, GL_ATI_texture_env_combine3, 
    GL_IBM_multimode_draw_arrays, GL_IBM_rasterpos_clip, 
    GL_IBM_texture_mirrored_repeat, GL_INGR_blend_func_separate, 
    GL_MESA_pack_invert, GL_MESA_texture_signed_rgba, GL_MESA_window_pos, 
    GL_MESA_ycbcr_texture, GL_NV_blend_square, GL_NV_depth_clamp, 
    GL_NV_light_max_exponent, GL_NV_packed_depth_stencil, 
    GL_NV_texgen_reflection, GL_NV_texture_env_combine4, 
    GL_NV_texture_rectangle, GL_NV_vertex_program1_1, GL_NV_vertex_program, 
    GL_SGIS_generate_mipmap, GL_SGIS_texture_border_clamp, 
    GL_SGIS_texture_edge_clamp, GL_SGIS_texture_lod, GL_SUN_multi_draw_arrays

32 GLX Visuals
    visual  x   bf lv rg d st  colorbuffer  sr ax dp st accumbuffer  ms  cav
  id dep cl sp  sz l  ci b ro  r  g  b  a F gb bf th cl  r  g  b  a ns b eat
----------------------------------------------------------------------------
0x021 24 tc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x022 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x08f 24 tc  0  24  0 r  . .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x090 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x091 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x092 24 tc  0  24  0 r  . .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x093 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x094 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x095 24 tc  0  32  0 r  . .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x096 24 tc  0  32  0 r  y .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x097 24 tc  0  32  0 r  y .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x098 24 tc  0  32  0 r  . .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x099 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x09a 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8 16 16 16  0  0 0 Slow
0x09b 24 tc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x09c 24 tc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8 16 16 16 16  0 0 Slow
0x09d 24 dc  0  24  0 r  . .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x09e 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x09f 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x0a0 24 dc  0  24  0 r  . .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x0a1 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x0a2 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x0a3 24 dc  0  32  0 r  . .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x0a4 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x0a5 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x0a6 24 dc  0  32  0 r  . .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x0a7 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x0a8 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x0a9 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8 16 16 16  0  0 0 Slow
0x0aa 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x0ab 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8 16 16 16 16  0 0 Slow
0x05e 32 tc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None

48 GLXFBConfigs:
    visual  x   bf lv rg d st  colorbuffer  sr ax dp st accumbuffer  ms  cav
  id dep cl sp  sz l  ci b ro  r  g  b  a F gb bf th cl  r  g  b  a ns b eat
----------------------------------------------------------------------------
0x05f  0 tc  0  16  0 r  . .   5  6  5  0 .  .  0  0  0  0  0  0  0  0 0 None
0x060  0 tc  0  16  0 r  y .   5  6  5  0 .  .  0  0  0  0  0  0  0  0 0 None
0x061  0 tc  0  16  0 r  y .   5  6  5  0 .  .  0  0  0  0  0  0  0  0 0 None
0x062  0 tc  0  16  0 r  . .   5  6  5  0 .  .  0 16  0  0  0  0  0  0 0 None
0x063  0 tc  0  16  0 r  y .   5  6  5  0 .  .  0 16  0  0  0  0  0  0 0 None
0x064  0 tc  0  16  0 r  y .   5  6  5  0 .  .  0 16  0  0  0  0  0  0 0 None
0x065 24 tc  0  24  0 r  . .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x066 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x067 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x068 24 tc  0  24  0 r  . .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x069 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x06a 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x06b 24 tc  0  32  0 r  . .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x06c 24 tc  0  32  0 r  y .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x06d 24 tc  0  32  0 r  y .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x06e 24 tc  0  32  0 r  . .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x06f 24 tc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x070 32 tc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x071  0 tc  0  16  0 r  y .   5  6  5  0 .  .  0 16  0  0  0  0  0  0 0 None
0x072  0 tc  0  16  0 r  y .   5  6  5  0 .  .  0 16  0 16 16 16  0  0 0 Slow
0x073 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x074 24 tc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8 16 16 16  0  0 0 Slow
0x075 24 tc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x076 24 tc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8 16 16 16 16  0 0 Slow
0x077  0 dc  0  16  0 r  . .   5  6  5  0 .  .  0  0  0  0  0  0  0  0 0 None
0x078  0 dc  0  16  0 r  y .   5  6  5  0 .  .  0  0  0  0  0  0  0  0 0 None
0x079  0 dc  0  16  0 r  y .   5  6  5  0 .  .  0  0  0  0  0  0  0  0 0 None
0x07a  0 dc  0  16  0 r  . .   5  6  5  0 .  .  0 16  0  0  0  0  0  0 0 None
0x07b  0 dc  0  16  0 r  y .   5  6  5  0 .  .  0 16  0  0  0  0  0  0 0 None
0x07c  0 dc  0  16  0 r  y .   5  6  5  0 .  .  0 16  0  0  0  0  0  0 0 None
0x07d 24 dc  0  24  0 r  . .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x07e 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x07f 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0  0  0  0  0  0  0  0 0 None
0x080 24 dc  0  24  0 r  . .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x081 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x082 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x083 24 dc  0  32  0 r  . .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x084 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x085 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0  0  0  0  0  0  0  0 0 None
0x086 24 dc  0  32  0 r  . .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x087 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x088 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x089  0 dc  0  16  0 r  y .   5  6  5  0 .  .  0 16  0  0  0  0  0  0 0 None
0x08a  0 dc  0  16  0 r  y .   5  6  5  0 .  .  0 16  0 16 16 16  0  0 0 Slow
0x08b 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8  0  0  0  0  0 0 None
0x08c 24 dc  0  24  0 r  y .   8  8  8  0 .  .  0 24  8 16 16 16  0  0 0 Slow
0x08d 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8  0  0  0  0  0 0 None
0x08e 24 dc  0  32  0 r  y .   8  8  8  8 .  .  0 24  8 16 16 16 16  0 0 Slow
Comment 1 christobzr 2011-08-29 05:01:16 UTC
Created attachment 50656 [details]
xorg log
Comment 2 christobzr 2011-08-29 05:12:24 UTC
Created attachment 50657 [details]
dmesg output (with boot option "drm.debug=0x06")
Comment 3 Chris Wilson 2011-09-07 14:23:42 UTC
The question to be asked is "which driver is the system missing that controls the backlight?"
Comment 4 christobzr 2011-09-19 05:51:47 UTC
> The question to be asked is "which driver is the system missing that controls
> the backlight?"

I'm not sure how to answer that question. In gentoo I compiled my own kernel with the following modules built in :

-> Device Drivers
  -> Graphics support
    -> Backlight & LCD device support
      -> Lowlevel LCD controls
      -> Platform LCD controls  
      -> Generic (aka Sharp Corgi) Backlight Driver 

Here is my full kernel configuration : http://pastebin.com/ViRaaESF
Comment 5 christobzr 2011-09-19 06:10:51 UTC
As suggested here http://forums.gentoo.org/viewtopic-p-6797468.html#6797468 , adding "acpi_osi= " or "acpi_osi=Linux" to the kernel boot command line in grub, lets me adjust brightness with the keys provided on the laptop (Fn + left/right arrow).

I added "acpi_osi=Linux" to grub so the machine now always boots with this parameter. It still boots to a blank screen, but I can press Fn + left arrow to switch the backlight on. Afterwards I can adjust the brightness with the keyboard controls.

The gnome-power-manager based brightness control applet does not work however.
Comment 6 christobzr 2011-10-12 01:20:44 UTC
Can I provide any further information ? If I'm not correctly describing the problem, is there somewhere I can go for advice ?
Comment 7 christobzr 2011-10-14 01:29:20 UTC
Am I to understand that this is not a problem in the Intel driver ?
Comment 8 Eugeni Dodonov 2011-10-14 13:25:18 UTC
I think it is one of the backlight issues, similar to #41306 or #36823.

There was one recent patch about a similar issue - http://lkml.org/lkml/2011/10/13/95 - could you try with it please?
Comment 9 christobzr 2011-10-19 01:53:08 UTC
Thanks for the feedback ! I patched my kernel with the suggested patch - same issue.

I would guess from the description of the patch that this is not the issue here : the patch seems to concern the backlight being set to wrong brightness when it goes up (not any incapacity to adjust brightness). This bug however is different, I will resume the issue a little more concisely.

If you just boot the system, the backlight is off and cannot be turned on with the brightness keys. If you can login without seeing what is on the screen, you can turn the backlight on with the command "setpci -s 00:02.0 F4.B=00", but it cannot be adjusted by keys or software, and will turn back off after lid shut, screensaver etc.

Adding "acpi_osi=Linux" to the kernel boot command line lets you switch on and adjust the backlight with the brightness keys after boot, but it cannot be adjusted by software. On boot the backlight is always off. Annoying consequences : system cannot dim display when idle or when on battery.

More banter here : http://dodonov.net/blog/2011/10/14/so-whats-been-up-with-intel-linux-graphics-this-week/
Comment 10 christobzr 2011-10-19 02:46:53 UTC
This bug seems to concern many  people : google gives tens of threads/bugs for issues with the same symptoms. ie :

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/752165
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/740893
http://markuswalther.com/tech/backlight.html
Comment 11 Eugeni Dodonov 2011-10-19 06:00:43 UTC
If it is a regression from previous kernel, I guess that the easiest way to get it solved by bisecting it to the patch which caused the problem..

@christobzr, as you can reproduce the problem consistently, could you do it for us please?

Thanks!
Comment 12 Jonathan Nieder 2012-01-01 10:50:49 UTC
*** Bug 44156 has been marked as a duplicate of this bug. ***
Comment 13 christobzr 2012-01-02 15:56:07 UTC
Btw, yes I will be happy to do the tests, however I do not currently have the machine...
Comment 14 Chris Wilson 2012-05-11 07:17:54 UTC
Daniel is working on some patches to fix the backlight controller and is looking for victims^Wtesters.
Comment 15 Daniel Vetter 2012-06-05 07:09:45 UTC
Ok, I've created these patches, available at http://cgit.freedesktop.org/~danvet/drm/log/?h=backlight-confusion

Git link is git://people.freedesktop.org/~danvet/drm backlight-confusion

Please test them, thanks.
Comment 16 Jani Nikula 2012-08-28 10:17:34 UTC
(In reply to comment #15)
> Ok, I've created these patches, available at
> http://cgit.freedesktop.org/~danvet/drm/log/?h=backlight-confusion
> 
> Git link is git://people.freedesktop.org/~danvet/drm backlight-confusion
> 
> Please test them, thanks.

Updated patches and discussion at [1], also available in the "backlight" branch of [2]. Please test.

[1] http://thread.gmane.org/gmane.comp.freedesktop.xorg.drivers.intel/13642
[2] git://gitorious.org/jani/drm.git
Comment 17 Jani Nikula 2012-09-17 12:39:17 UTC
Please try i915.invert_brightness=1 module parameter with kernel version v3.5 or later, see if that fixes the brightness issue, and report 'lspci -vmmnn' if it does.
Comment 18 Jesse Barnes 2012-12-11 19:15:36 UTC
If someone finds the time to test and this is still an issue, please re-open