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    SubjectRe: [PATCHv4 08/10] backlight: add TI LMU backlight driver
    Hi!

    > > > +static int ti_lmu_bl_add_device(struct ti_lmu_bank *lmu_bank)
    > > > +{
    > > > + switch (lmu_bank->type) {
    > > > + case TI_LMU_BL:
    > > > + return ti_lmu_bl_register_backlight(lmu_bank);
    > > > + case TI_LMU_LED:
    > > > + return ti_lmu_bl_register_led(lmu_bank);
    > > > + default:
    > > > + return -EINVAL;
    > > > + }
    > > > +}
    > >
    > > Ok, this is somehow unusual/crazy. Single driver with two
    > > interfaces.
    > >
    > > Do we need the LED interface for something?
    > >
    > > If yes, I believe reasonable solution would be to always provide LED
    > > interface, and then have "backlight-trigger" which that would provide
    > > backlight interface for arbitrary LED.
    >
    > Userspace expects keyboard backlight to be exposed via the LED
    > subsystem and display backlight via the backlight subsystem.

    Ok.

    > I considered always exposing the banks via the LED subsystem and
    > using a generic backlight driver. That brings its own problems,
    > since there is a dependency between the display and the backlight.
    > This is described in DT using a phandle. Getting the right backlight
    > device from the phandle will become very tricky with this approach.

    I believe we have to do this.

    Virtually any LED can be used as a backlight, and we don't really want
    to add two personalities to all the LED drivers.

    And it should not be too bad: LED will just have default trigger,
    which will say this LED corresponds to this display device. I believe
    someone wanted to do that for USB/ethernet activity.

    Pavel
    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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