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    SubjectRe: [PATCH 0/3] pwm-backlight: add subdrivers & Tegra support
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    Hi Thierry,

    On Monday 21 January 2013 15:49:28 Thierry Reding wrote:
    > Eventually this should all be covered by the CDF, but since that's not
    > ready yet we want something ad-hoc to get the hardware supported. As
    > such I would like to see this go into some sort of minimalistic, Tegra-
    > specific display/panel framework. I'd prefer to keep the pwm-backlight
    > driver as simple and generic as possible, that is, a driver for a PWM-
    > controlled backlight.
    >
    > Another advantage of moving this into a sort of display framework is
    > that it may help in defining the requirements for a CDF and that moving
    > the code to the CDF should be easier once it is done.
    >
    > Last but not least, abstracting away the panel allows other things such
    > as physical dimensions and display modes to be properly encapsulated. I
    > think that power-on/off timing requirements for panels also belong to
    > this set since they are usually specific to a given panel.
    >
    > Maybe adding these drivers to tegra-drm for now would be a good option.
    > That way the corresponding glue can be added without a need for inter-
    > tree dependencies.

    IIRC (because that was a while ago already) having a Tegra-only display
    framework is exactly what we wanted to avoid in the first place. This series
    does nothing but leverage the callbacks mechanism that already exists in pwm-
    backlight and make it available to DT systems. If we start making a Tegra-
    specific solution, then other architectures will have to reinvent the wheel
    again. I really don't think we want to go that way.

    These patches only makes slight changes to pwm_bl.c and do not extend its
    capabilities. I agree that a suitable solution will require the CDF, but by
    the meantime, let's go for the practical route instead of repeating the same
    mistakes (i.e. architecture-specific frameworks) again.

    There are certainly better ways to do this, but I'm not convinced at all that
    a Tegra-only solution is one of them.

    Alex.



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