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    SubjectRe: [RFC PATCH 11/11] arm/versatile: Add device tree support
    On Thu, Jun 16, 2011 at 04:20:37PM +0200, Arnd Bergmann wrote:
    > On Thursday 16 June 2011, Grant Likely wrote:
    > > This patch adds a new versatile platform for when using the device
    > > tree. Add platform and amba devices are discovered and registered by
    > > parsing the device tree. Clocks and initial io mappings are still
    > > configured statically.
    >
    > Hi Grant,
    >
    > Two small questions about the device tree contents:
    >
    > > + i2c@10002000 {
    > > + #address-cells = <1>;
    > > + #size-cells = <0>;
    > > + compatible = "arm,versatile-i2c";
    > > + reg = <0x10002000 0x1000>;
    > > +
    > > + rtc@68 {
    > > + compatible = "dallas,ds1338";
    > > + reg = <0x68>;
    > > + };
    > > + };
    > > +
    > > + net@10010000 {
    > > + compatible = "smsc,lan91c111";
    > > + reg = <0x10010000 0x10000>;
    > > + interrupts = <25>;
    > > + };
    > > +
    > > + lcd@10008000 {
    > > + compatible = "arm,versatile-lcd";
    > > + reg = <0x10008000 0x1000>;
    > > + };
    >
    > Why are these devices on the top level, rather than on the AMBA bus or
    > the FPGA? From the documentation, it seems that they are implemented
    > in the FPGA, which would also match the address layout.

    Mostly because I 'faked' this device tree based on what is currently
    in the kernel for the Versatile platform. I need to look at the
    documentation and make it reflect reality, including setting up ranges
    correctly (as you commented on below).

    >
    > > + amba {
    > > + compatible = "arm,amba-bus";
    > > + #address-cells = <1>;
    > > + #size-cells = <1>;
    > > + ranges;
    > > +
    > > + vic: intc@10140000 {
    > > + compatible = "arm,versatile-vic", "arm,vic";
    > > + interrupt-controller;
    > > + #interrupt-cells = <1>;
    > > + reg = <0x10140000 0x1000>;
    > > + };
    > > +
    >
    > Why the empty ranges property? All device registers are based on 0x10000000,
    > so I'd expect this to be described like that here.
    >
    > Arnd


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