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@@ -0,0 +1,30 @@ +libbacklight provides an abstraction layer that allows applications to +identify the appropriate Linux backlight device for their use. The API is +straightforward. + +struct backlight *backlight = backlight_init(dev, card, connector_type, + connector_type_id); + +You must provide either dev and/or card, connector_type and connector_type_id. +dev is a pciaccess struct pci_device representing your card. This will find +the backlight device associated with your pci device. card is the drm card +number. connector_type is the drm connector type. connector_type_id is the +specific instance of that connector_type on the given card. + +libbacklight will then scan all available backlight devices, looking for a +device that matches the given constraints. In general, if the connector type +is LVDS or eDP then a firmware device will be preferred if available - if +not, a platform device will be chosen, and finally a raw device. Firmware +and raw devices will be ignored unless their parents match the PCI device +or connector provided. For non-LVDS/eDP devices, platform devices will +typically not be used. + +Once a backlight structure has been provided it can be queried via: + +backlight_get_max_brightness() (provides the maximum brightness) +backlight_get_brightness() (provides the cached brightness) +backlight_get_actual_brightness() (provides the brightness as reported by the + device) +backlight_set_brightness() (sets the brightness to a value between 0 and max) + +backlight_destroy() will free the resources associated with the device.
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