1*4882a593SmuzhiyunWhat: /sys/class/backlight/<backlight>/bl_power 2*4882a593SmuzhiyunDate: April 2005 3*4882a593SmuzhiyunKernelVersion: 2.6.12 4*4882a593SmuzhiyunContact: Richard Purdie <rpurdie@rpsys.net> 5*4882a593SmuzhiyunDescription: 6*4882a593Smuzhiyun Control BACKLIGHT power, values are FB_BLANK_* from fb.h 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun - FB_BLANK_UNBLANK (0) : power on. 9*4882a593Smuzhiyun - FB_BLANK_POWERDOWN (4) : power off 10*4882a593SmuzhiyunUsers: HAL 11*4882a593Smuzhiyun 12*4882a593SmuzhiyunWhat: /sys/class/backlight/<backlight>/brightness 13*4882a593SmuzhiyunDate: April 2005 14*4882a593SmuzhiyunKernelVersion: 2.6.12 15*4882a593SmuzhiyunContact: Richard Purdie <rpurdie@rpsys.net> 16*4882a593SmuzhiyunDescription: 17*4882a593Smuzhiyun Control the brightness for this <backlight>. Values 18*4882a593Smuzhiyun are between 0 and max_brightness. This file will also 19*4882a593Smuzhiyun show the brightness level stored in the driver, which 20*4882a593Smuzhiyun may not be the actual brightness (see actual_brightness). 21*4882a593SmuzhiyunUsers: HAL 22*4882a593Smuzhiyun 23*4882a593SmuzhiyunWhat: /sys/class/backlight/<backlight>/actual_brightness 24*4882a593SmuzhiyunDate: March 2006 25*4882a593SmuzhiyunKernelVersion: 2.6.17 26*4882a593SmuzhiyunContact: Richard Purdie <rpurdie@rpsys.net> 27*4882a593SmuzhiyunDescription: 28*4882a593Smuzhiyun Show the actual brightness by querying the hardware. 29*4882a593SmuzhiyunUsers: HAL 30*4882a593Smuzhiyun 31*4882a593SmuzhiyunWhat: /sys/class/backlight/<backlight>/max_brightness 32*4882a593SmuzhiyunDate: April 2005 33*4882a593SmuzhiyunKernelVersion: 2.6.12 34*4882a593SmuzhiyunContact: Richard Purdie <rpurdie@rpsys.net> 35*4882a593SmuzhiyunDescription: 36*4882a593Smuzhiyun Maximum brightness for <backlight>. 37*4882a593SmuzhiyunUsers: HAL 38*4882a593Smuzhiyun 39*4882a593SmuzhiyunWhat: /sys/class/backlight/<backlight>/type 40*4882a593SmuzhiyunDate: September 2010 41*4882a593SmuzhiyunKernelVersion: 2.6.37 42*4882a593SmuzhiyunContact: Matthew Garrett <mjg@redhat.com> 43*4882a593SmuzhiyunDescription: 44*4882a593Smuzhiyun The type of interface controlled by <backlight>. 45*4882a593Smuzhiyun "firmware": The driver uses a standard firmware interface 46*4882a593Smuzhiyun "platform": The driver uses a platform-specific interface 47*4882a593Smuzhiyun "raw": The driver controls hardware registers directly 48*4882a593Smuzhiyun 49*4882a593Smuzhiyun In the general case, when multiple backlight 50*4882a593Smuzhiyun interfaces are available for a single device, firmware 51*4882a593Smuzhiyun control should be preferred to platform control should 52*4882a593Smuzhiyun be preferred to raw control. Using a firmware 53*4882a593Smuzhiyun interface reduces the probability of confusion with 54*4882a593Smuzhiyun the hardware and the OS independently updating the 55*4882a593Smuzhiyun backlight state. Platform interfaces are mostly a 56*4882a593Smuzhiyun holdover from pre-standardisation of firmware 57*4882a593Smuzhiyun interfaces. 58