Problem with ACPI video

[Luis Henriques <henrix@sapo.pt>]

It seems that there is a problem with my video card.  I got the
following message:

[...]

[   14.705248] input: Video Bus as /class/input/input4
[   14.757151] ACPI: Video Device [VGA] (multi-head: yes  rom: no  post: no)
[   14.757624] proc_dir_entry 'VGA' already registered
[   14.757673] Pid: 3093, comm: modprobe Not tainted
2.6.27-rc5-00006-gbef69ea #1
[   14.757723]
[   14.757724] Call Trace:
[   14.757816]  [<ffffffff8032199c>] proc_register+0x1dc/0x210
[   14.757866]  [<ffffffff80321bed>] proc_mkdir_mode+0x3d/0x60
[   14.757913]  [<ffffffff80321c21>] proc_mkdir+0x11/0x20
[   14.757963]  [<ffffffffa01d27cc>] acpi_video_bus_add+0x1e9/0xd55 [video]
[   14.758011]  [<ffffffff8032cb98>] ? sysfs_do_create_link+0xc8/0x160
[   14.758060]  [<ffffffff803bfa16>] acpi_device_probe+0x49/0x8c
[   14.758108]  [<ffffffff803f7f02>] driver_probe_device+0xa2/0x1e0
[   14.758156]  [<ffffffff803f80cb>] __driver_attach+0x8b/0x90
[   14.758202]  [<ffffffff803f8040>] ? __driver_attach+0x0/0x90
[   14.758249]  [<ffffffff803f76ab>] bus_for_each_dev+0x6b/0xa0
[   14.758297]  [<ffffffff802c9636>] ? kmem_cache_alloc+0x86/0xc0
[   14.758344]  [<ffffffff803f7d4c>] driver_attach+0x1c/0x20
[   14.758391]  [<ffffffff803f6ef8>] bus_add_driver+0x1f8/0x270
[   14.758439]  [<ffffffffa00e5000>] ? acpi_video_init+0x0/0x5e [video]
[   14.758487]  [<ffffffff803f82b0>] driver_register+0x70/0x160
[   14.758535]  [<ffffffffa00e5000>] ? acpi_video_init+0x0/0x5e [video]
[   14.758582]  [<ffffffff803bfd4e>] acpi_bus_register_driver+0x3e/0x40
[   14.758630]  [<ffffffffa00e503c>] acpi_video_init+0x3c/0x5e [video]
[   14.758677]  [<ffffffff80209040>] _stext+0x40/0x1a0
[   14.758726]  [<ffffffff802704cd>] sys_init_module+0xad/0x1e0
[   14.758772]  [<ffffffff8020c62a>] system_call_fastpath+0x16/0x1b
[   14.758818]
[   14.768981] acpi device:29: registered as cooling_device3
[   14.769252] input: Video Bus as /class/input/input5
[   14.817141] ACPI: Video Device [VGA] (multi-head: yes  rom: no  post: no)
[   14.905143] ACPI: Battery Slot [BAT1] (battery present)
[...]

It seems that acpi_video_bus_add function is invoked twice and, the
second time, it fails (maybe it is supposed to be invoked twice...).

Anyway, I can not tell you what was the first kernel where this problem
occured since the laptop is new and had this problem on all kernels I
tried (this one is Linus git-tree 2.6.27-rc5-00006-gbef69ea).

Also found out that I have two directories /proc/acpi/video/VGA/.

After looking at the code, I found the following code:

  if (!strcmp(device->pnp.bus_id, "VID")) {
        if (instance)
              device->pnp.bus_id[3] = '0' + instance;
        instance ++;
  }

in drivers/acpi/video.c.  Is this code supposed to solve a similar
problem as the one I am facing?

Please let me know whether you need any additional information to help
me solving this problem.

--
Luis