13c4c1b69SCorentin CharyWhat: /sys/class/backlight/<backlight>/bl_power 23c4c1b69SCorentin CharyDate: April 2005 33c4c1b69SCorentin CharyKernelVersion: 2.6.12 43c4c1b69SCorentin CharyContact: Richard Purdie <rpurdie@rpsys.net> 53c4c1b69SCorentin CharyDescription: 6a1cacb8aSThomas Zimmermann Control BACKLIGHT power, values are compatible with 7a1cacb8aSThomas Zimmermann FB_BLANK_* from fb.h 898913408SMauro Carvalho Chehab 9a1cacb8aSThomas Zimmermann - 0 (FB_BLANK_UNBLANK) : power on. 10a1cacb8aSThomas Zimmermann - 4 (FB_BLANK_POWERDOWN) : power off 113c4c1b69SCorentin CharyUsers: HAL 123c4c1b69SCorentin Chary 133c4c1b69SCorentin CharyWhat: /sys/class/backlight/<backlight>/brightness 143c4c1b69SCorentin CharyDate: April 2005 153c4c1b69SCorentin CharyKernelVersion: 2.6.12 163c4c1b69SCorentin CharyContact: Richard Purdie <rpurdie@rpsys.net> 173c4c1b69SCorentin CharyDescription: 183c4c1b69SCorentin Chary Control the brightness for this <backlight>. Values 193c4c1b69SCorentin Chary are between 0 and max_brightness. This file will also 203c4c1b69SCorentin Chary show the brightness level stored in the driver, which 213c4c1b69SCorentin Chary may not be the actual brightness (see actual_brightness). 223c4c1b69SCorentin CharyUsers: HAL 233c4c1b69SCorentin Chary 243c4c1b69SCorentin CharyWhat: /sys/class/backlight/<backlight>/actual_brightness 253c4c1b69SCorentin CharyDate: March 2006 263c4c1b69SCorentin CharyKernelVersion: 2.6.17 273c4c1b69SCorentin CharyContact: Richard Purdie <rpurdie@rpsys.net> 283c4c1b69SCorentin CharyDescription: 29*8ecd32b6SMario Limonciello Show the actual brightness by querying the hardware. Due 30*8ecd32b6SMario Limonciello to implementation differences in hardware this may not 31*8ecd32b6SMario Limonciello match the value in 'brightness'. For example some hardware 32*8ecd32b6SMario Limonciello may treat blanking differently or have custom power saving 33*8ecd32b6SMario Limonciello features. Userspace should generally use the values in 34*8ecd32b6SMario Limonciello 'brightness' to make decisions. 353c4c1b69SCorentin CharyUsers: HAL 363c4c1b69SCorentin Chary 373c4c1b69SCorentin CharyWhat: /sys/class/backlight/<backlight>/max_brightness 383c4c1b69SCorentin CharyDate: April 2005 393c4c1b69SCorentin CharyKernelVersion: 2.6.12 403c4c1b69SCorentin CharyContact: Richard Purdie <rpurdie@rpsys.net> 413c4c1b69SCorentin CharyDescription: 423c4c1b69SCorentin Chary Maximum brightness for <backlight>. 433c4c1b69SCorentin CharyUsers: HAL 44bb7ca747SMatthew Garrett 45bb7ca747SMatthew GarrettWhat: /sys/class/backlight/<backlight>/type 46bb7ca747SMatthew GarrettDate: September 2010 47bb7ca747SMatthew GarrettKernelVersion: 2.6.37 48bb7ca747SMatthew GarrettContact: Matthew Garrett <mjg@redhat.com> 49bb7ca747SMatthew GarrettDescription: 50bb7ca747SMatthew Garrett The type of interface controlled by <backlight>. 51bb7ca747SMatthew Garrett "firmware": The driver uses a standard firmware interface 52bb7ca747SMatthew Garrett "platform": The driver uses a platform-specific interface 53bb7ca747SMatthew Garrett "raw": The driver controls hardware registers directly 54bb7ca747SMatthew Garrett 55bb7ca747SMatthew Garrett In the general case, when multiple backlight 56bb7ca747SMatthew Garrett interfaces are available for a single device, firmware 57bb7ca747SMatthew Garrett control should be preferred to platform control should 58bb7ca747SMatthew Garrett be preferred to raw control. Using a firmware 59bb7ca747SMatthew Garrett interface reduces the probability of confusion with 60bb7ca747SMatthew Garrett the hardware and the OS independently updating the 61bb7ca747SMatthew Garrett backlight state. Platform interfaces are mostly a 62bb7ca747SMatthew Garrett holdover from pre-standardisation of firmware 63bb7ca747SMatthew Garrett interfaces. 64