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


** Tags added: kernel-bug-exists-upstream

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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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