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    SubjectRe: Backlight device class redesign
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    W dniu 28 listopada 2009 01:30 użytkownik Rafał Miłecki
    <zajec5@gmail.com> napisał:
    > As discussed in http://marc.info/?t=124947671300008&r=1&w=2 we need to
    > redesign our backlight device class.

    I was trying to make it work this way:
    1. Everytime register request comes, look for backlight_display with given name.
    1. A. If needed, create new backlight_display
    2. Add new device to devices list of backlight_display
    3. Find best device on devices list of backlight_display
    4. Register if under /sys/class/backlight/name_of_display

    This didn't work because of registering only the best device. Look at
    this code in drivers/acpi/video.c:

    device->backlight = backlight_device_register(name,
    NULL, device, &acpi_backlight_ops);
    (...)
    result = sysfs_create_link(&device->backlight->dev.kobj,
    &device->dev->dev.kobj, "device");

    It expects device to be registered (have dev.kobj) after calling
    backlight_device_register.

    So in summary we just can not do lazy registration. Every device
    passed to backlight_device_register has to be registered in that
    function or never.

    So I think we have to register every device and just keep symlink
    /sys/class/backlight/display_name pointing best device. We could
    register devices in
    1) /sys/class/backlight/.devicename (hidden)
    2) some /sys/class/internal-usage/devicename

    Do you agree on this?

    --
    Rafał
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