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    SubjectRe: [PATCH 2/3] tegra: pwm-backlight: add tegra pwm-bl driver
    On 01/21/2013 04:24 PM, Alex Courbot wrote:
    > On Monday 21 January 2013 15:35:58 Mark Zhang wrote:
    >>> + backlight {
    >>> + compatible = "pwm-backlight-ventana";
    >>> + brightness-levels = <0 16 32 48 64 80 96 112 128 144 160 176 192
    > 208
    >>> 224 240 255>; + default-brightness-level = <12>;
    >>> +
    >>> + pwms = <&pwm 2 5000000>;
    >>
    >> After read the codes of tegra pwm driver & pwm framework, I got to know
    >> the meaning of this property. So I think we need to add a doc(e.g:
    >> Documentation/devicetree/bindings/video/backlight/nvidia,tegra20-bl.txt)
    >> to explain this, "Documentation/devicetree/bindings/pwm/pwm.txt" doesn't
    >> explain this, because this may be different between different pwm drivers.
    >
    > The bindings are in Documentation/devicetree/bindings/video/backlight/pwm-
    > backlight.txt . But you are right that the power supplies and GPIO will
    > require a description of their own - I omitted it for this version because I
    > am not sure what the driver should be called.
    >

    The description of this property in pwm-backlight.txt is:

    "pwms: OF device-tree PWM specification (see PWM binding[0])
    [0]: Documentation/devicetree/bindings/pwm/pwm.txt"

    So you can't get any useful infos from that. That's why I propose to add
    a tegra specific doc in
    "Documentation/devicetree/bindings/video/backlight" directory.

    > The panel used on Ventana is a Chunghwa CLAA101WA01A, maybe that's the name we
    > should use for the compatible string instead (and rename the driver
    > accordingly).
    >
    >> So according to the filename, I think we can put all tegra boards codes
    >> here, right? Just like what you do for Ventana, if I wanna add support
    >> for cardhu, I can define similar functions -- let's say "init_cardhu",
    >> "exit_cardhu", "notify_cardhu" and "notify_after_cardhu", right?
    >
    > That was my initial intention, yes.
    >
    >> But I think if we do in this way, the file will become very long soon.
    >> And there are a lot of redundant codes in it. So do you have any
    >> suggestions?
    >
    > If we decide to make a "Tegra" driver, then I don't think the size of the file
    > is a big issues, as long as one can easily navigate into it. It will make
    > sense to do this since Tegra kernels should include support for all the
    > boards.
    >
    > If we go and name the drivers after their actual panel names, we should
    > definitely put them into separate files. The Tegra configuration could then
    > include them all by default to make sure all boards are supported.

    I don't think use panel name instead of board name is a good idea.
    Developers may not be familiar with panel names. So if we use panel
    name, we have to search and read a lot of manual to find out what the
    panel is.

    I'd rather putting all stuffs in pwm_bl_tegra.c than separating them.

    Mark
    >
    > Alex.
    >


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