1d55c028fSMatthias KaehlckeWhat: /sys/class/backlight/<backlight>/scale 2d55c028fSMatthias KaehlckeDate: July 2019 3d55c028fSMatthias KaehlckeKernelVersion: 5.4 4d55c028fSMatthias KaehlckeContact: Daniel Thompson <daniel.thompson@linaro.org> 5d55c028fSMatthias KaehlckeDescription: 6d55c028fSMatthias Kaehlcke Description of the scale of the brightness curve. 7d55c028fSMatthias Kaehlcke 8d55c028fSMatthias Kaehlcke The human eye senses brightness approximately logarithmically, 9d55c028fSMatthias Kaehlcke hence linear changes in brightness are perceived as being 10d55c028fSMatthias Kaehlcke non-linear. To achieve a linear perception of brightness changes 11d55c028fSMatthias Kaehlcke controls like sliders need to apply a logarithmic mapping for 12d55c028fSMatthias Kaehlcke backlights with a linear brightness curve. 13d55c028fSMatthias Kaehlcke 14d55c028fSMatthias Kaehlcke Possible values of the attribute are: 15d55c028fSMatthias Kaehlcke 16d55c028fSMatthias Kaehlcke unknown 17d55c028fSMatthias Kaehlcke The scale of the brightness curve is unknown. 18d55c028fSMatthias Kaehlcke 19d55c028fSMatthias Kaehlcke linear 20d55c028fSMatthias Kaehlcke The brightness changes linearly with each step. Brightness 21d55c028fSMatthias Kaehlcke controls should apply a logarithmic mapping for a linear 22d55c028fSMatthias Kaehlcke perception. 23d55c028fSMatthias Kaehlcke 24d55c028fSMatthias Kaehlcke non-linear 25d55c028fSMatthias Kaehlcke The brightness changes non-linearly with each step. Brightness 26d55c028fSMatthias Kaehlcke controls should use a linear mapping for a linear perception. 27bd6e8441SMauro Carvalho Chehab 28bd6e8441SMauro Carvalho ChehabWhat: /sys/class/backlight/<backlight>/ambient_light_level 29bd6e8441SMauro Carvalho ChehabDate: Apr, 2010 30bd6e8441SMauro Carvalho ChehabKernelVersion: v2.6.35 31bd6e8441SMauro Carvalho ChehabContact: Michael Hennerich <michael.hennerich@analog.com> 32bd6e8441SMauro Carvalho ChehabDescription: 33bd6e8441SMauro Carvalho Chehab (RO) Get conversion value of the light sensor. 34bd6e8441SMauro Carvalho Chehab 35bd6e8441SMauro Carvalho Chehab The value is automatically updated every 80 ms when the 36bd6e8441SMauro Carvalho Chehab light sensor is enabled. 37bd6e8441SMauro Carvalho Chehab 38bd6e8441SMauro Carvalho Chehab The value range is device-driver specific: 39bd6e8441SMauro Carvalho Chehab 40bd6e8441SMauro Carvalho Chehab For ADP8870: 41bd6e8441SMauro Carvalho Chehab 42bd6e8441SMauro Carvalho Chehab It returns integer between 0 (dark) and 8000 (max ambient 43bd6e8441SMauro Carvalho Chehab brightness). 44bd6e8441SMauro Carvalho Chehab 45bd6e8441SMauro Carvalho Chehab For ADP8860: 46bd6e8441SMauro Carvalho Chehab 47bd6e8441SMauro Carvalho Chehab It returns a 13-bits integer. 48bd6e8441SMauro Carvalho Chehab 49bd6e8441SMauro Carvalho ChehabWhat: /sys/class/backlight/<backlight>/ambient_light_zone 50bd6e8441SMauro Carvalho ChehabDate: Apr, 2010 51bd6e8441SMauro Carvalho ChehabKernelVersion: v2.6.35 52bd6e8441SMauro Carvalho ChehabContact: Michael Hennerich <michael.hennerich@analog.com>, 53bd6e8441SMauro Carvalho Chehab device-drivers-devel@blackfin.uclinux.org 54bd6e8441SMauro Carvalho Chehab 55bd6e8441SMauro Carvalho ChehabDescription: 56bd6e8441SMauro Carvalho Chehab (RW) Read or write the specific brightness level at which the 57bd6e8441SMauro Carvalho Chehab backlight operates. 58bd6e8441SMauro Carvalho Chehab 59bd6e8441SMauro Carvalho Chehab The value meaning is device-driver specific: 60bd6e8441SMauro Carvalho Chehab 61bd6e8441SMauro Carvalho Chehab For ADP8860: 62bd6e8441SMauro Carvalho Chehab 63bd6e8441SMauro Carvalho Chehab == ========================== 64bd6e8441SMauro Carvalho Chehab 0 Off: Backlight set to 0 mA 65bd6e8441SMauro Carvalho Chehab 1 Level 1: daylight 66bd6e8441SMauro Carvalho Chehab 2 Level 2: bright 67bd6e8441SMauro Carvalho Chehab 3 Level 3: dark 68bd6e8441SMauro Carvalho Chehab == ========================== 69bd6e8441SMauro Carvalho Chehab 70bd6e8441SMauro Carvalho Chehab For ADP8870: 71bd6e8441SMauro Carvalho Chehab 72bd6e8441SMauro Carvalho Chehab == ========================== 73bd6e8441SMauro Carvalho Chehab 0 Off: Backlight set to 0 mA 74bd6e8441SMauro Carvalho Chehab 1 Level 1: daylight 75bd6e8441SMauro Carvalho Chehab 2 Level 2: bright 76bd6e8441SMauro Carvalho Chehab 3 Level 3: office 77bd6e8441SMauro Carvalho Chehab 4 Level 4: indoor 78bd6e8441SMauro Carvalho Chehab 5 Level 5: dark 79bd6e8441SMauro Carvalho Chehab == ========================== 80bd6e8441SMauro Carvalho Chehab 81bd6e8441SMauro Carvalho Chehab Writing 0 returns to normal/automatic ambient light level 82bd6e8441SMauro Carvalho Chehab operation. 83bd6e8441SMauro Carvalho Chehab 84bd6e8441SMauro Carvalho Chehab It can be enabled by writing the value stored in 85bd6e8441SMauro Carvalho Chehab /sys/class/backlight/<backlight>/max_brightness to 86bd6e8441SMauro Carvalho Chehab /sys/class/backlight/<backlight>/brightness. 87