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[Bug 1478696] Re: dell-laptop: Incorrect keyboard backlight detection


This issue appears to be an upstream bug, since you tested the latest
upstream kernel. Would it be possible for you to open an upstream bug
report[0]? That will allow the upstream Developers to examine the issue,
and may provide a quicker resolution to the bug.

Please follow the instructions on the wiki page[0]. The first step is to
email the appropriate mailing list. If no response is received, then a
bug may be opened on bugzilla.kernel.org.

Once this bug is reported upstream, please add the tag: 'kernel-bug-

[0] https://wiki.ubuntu.com/Bugs/Upstream/kernel

** Changed in: linux (Ubuntu)
       Status: Incomplete => Triaged

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  dell-laptop: Incorrect keyboard backlight detection

Status in linux package in Ubuntu:

Bug description:
  I own Dell Inspiron M5110 (Q15R). This laptop has no keyboard backlight, but dell-laptop claims otherwise.
  My syslog was getting spammed with "Keyboard brightness level control not supported" as dell-laptop was trying to get/set backlight values.

  In dell-laptop there is kbd_led_present variable, but on my M5110 it's
  being set to true:

  	ret = kbd_init_info();
  	if (kbd_token_bits != 0 || ret == 0)
  		kbd_led_present = true;

  kbd_token_bits is 0, but so is ret.
  kbd_init_info method is only returning != 0 if kbd_get_info is returning != 0

  (Basing on this: http://linux.dell.com/cgi-bin/cgit.cgi/libsmbios.git/tree/src/bin/smbios-keyboard-ctl#n667)
  kbd_get_info method returns only cbRES1 value of following smbios call :
  cbClass 4
  cbSelect 11
  cbArg1 0x0
  And it returns 0...
  I found that any cbRES of this call is giving me nothing but zeros, as if it wasn't defined in my BIOS. I have it's newest version for my laptop:
  [    0.000000] SMBIOS 2.7 present.
  [    0.000000] DMI: Dell Inc. Inspiron M5110/0X7W03, BIOS A05 03/22/2012

  However, if "cbRES3, byte2  Number of keyboard light brightness
  levels" is 0 as well, that should mean backlight is not available,
  right? I'm attaching possible fix.

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