1*4882a593SmuzhiyunWhat: /sys/class/backlight/<backlight>/scale 2*4882a593SmuzhiyunDate: July 2019 3*4882a593SmuzhiyunKernelVersion: 5.4 4*4882a593SmuzhiyunContact: Daniel Thompson <daniel.thompson@linaro.org> 5*4882a593SmuzhiyunDescription: 6*4882a593Smuzhiyun Description of the scale of the brightness curve. 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun The human eye senses brightness approximately logarithmically, 9*4882a593Smuzhiyun hence linear changes in brightness are perceived as being 10*4882a593Smuzhiyun non-linear. To achieve a linear perception of brightness changes 11*4882a593Smuzhiyun controls like sliders need to apply a logarithmic mapping for 12*4882a593Smuzhiyun backlights with a linear brightness curve. 13*4882a593Smuzhiyun 14*4882a593Smuzhiyun Possible values of the attribute are: 15*4882a593Smuzhiyun 16*4882a593Smuzhiyun unknown 17*4882a593Smuzhiyun The scale of the brightness curve is unknown. 18*4882a593Smuzhiyun 19*4882a593Smuzhiyun linear 20*4882a593Smuzhiyun The brightness changes linearly with each step. Brightness 21*4882a593Smuzhiyun controls should apply a logarithmic mapping for a linear 22*4882a593Smuzhiyun perception. 23*4882a593Smuzhiyun 24*4882a593Smuzhiyun non-linear 25*4882a593Smuzhiyun The brightness changes non-linearly with each step. Brightness 26*4882a593Smuzhiyun controls should use a linear mapping for a linear perception. 27*4882a593Smuzhiyun 28*4882a593SmuzhiyunWhat: /sys/class/backlight/<backlight>/ambient_light_level 29*4882a593SmuzhiyunDate: Apr, 2010 30*4882a593SmuzhiyunKernelVersion: v2.6.35 31*4882a593SmuzhiyunContact: Michael Hennerich <michael.hennerich@analog.com> 32*4882a593SmuzhiyunDescription: 33*4882a593Smuzhiyun (RO) Get conversion value of the light sensor. 34*4882a593Smuzhiyun 35*4882a593Smuzhiyun The value is automatically updated every 80 ms when the 36*4882a593Smuzhiyun light sensor is enabled. 37*4882a593Smuzhiyun 38*4882a593Smuzhiyun The value range is device-driver specific: 39*4882a593Smuzhiyun 40*4882a593Smuzhiyun For ADP8870: 41*4882a593Smuzhiyun 42*4882a593Smuzhiyun It returns integer between 0 (dark) and 8000 (max ambient 43*4882a593Smuzhiyun brightness). 44*4882a593Smuzhiyun 45*4882a593Smuzhiyun For ADP8860: 46*4882a593Smuzhiyun 47*4882a593Smuzhiyun It returns a 13-bits integer. 48*4882a593Smuzhiyun 49*4882a593SmuzhiyunWhat: /sys/class/backlight/<backlight>/ambient_light_zone 50*4882a593SmuzhiyunDate: Apr, 2010 51*4882a593SmuzhiyunKernelVersion: v2.6.35 52*4882a593SmuzhiyunContact: Michael Hennerich <michael.hennerich@analog.com>, 53*4882a593Smuzhiyun device-drivers-devel@blackfin.uclinux.org 54*4882a593Smuzhiyun 55*4882a593SmuzhiyunDescription: 56*4882a593Smuzhiyun (RW) Read or write the specific brightness level at which the 57*4882a593Smuzhiyun backlight operates. 58*4882a593Smuzhiyun 59*4882a593Smuzhiyun The value meaning is device-driver specific: 60*4882a593Smuzhiyun 61*4882a593Smuzhiyun For ADP8860: 62*4882a593Smuzhiyun 63*4882a593Smuzhiyun == ========================== 64*4882a593Smuzhiyun 0 Off: Backlight set to 0 mA 65*4882a593Smuzhiyun 1 Level 1: daylight 66*4882a593Smuzhiyun 2 Level 2: bright 67*4882a593Smuzhiyun 3 Level 3: dark 68*4882a593Smuzhiyun == ========================== 69*4882a593Smuzhiyun 70*4882a593Smuzhiyun For ADP8870: 71*4882a593Smuzhiyun 72*4882a593Smuzhiyun == ========================== 73*4882a593Smuzhiyun 0 Off: Backlight set to 0 mA 74*4882a593Smuzhiyun 1 Level 1: daylight 75*4882a593Smuzhiyun 2 Level 2: bright 76*4882a593Smuzhiyun 3 Level 3: office 77*4882a593Smuzhiyun 4 Level 4: indoor 78*4882a593Smuzhiyun 5 Level 5: dark 79*4882a593Smuzhiyun == ========================== 80*4882a593Smuzhiyun 81*4882a593Smuzhiyun Writing 0 returns to normal/automatic ambient light level 82*4882a593Smuzhiyun operation. 83*4882a593Smuzhiyun 84*4882a593Smuzhiyun It can be enabled by writing the value stored in 85*4882a593Smuzhiyun /sys/class/backlight/<backlight>/max_brightness to 86*4882a593Smuzhiyun /sys/class/backlight/<backlight>/brightness. 87