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    SubjectRe: [PATCH v3 05/11] dt-bindings: i3c: Document core bindings
    Hi Rob,

    On Mon, 26 Mar 2018 17:24:58 -0500
    Rob Herring <robh@kernel.org> wrote:

    > > +
    > > +I3C devices
    > > +===========
    > > +
    > > +All I3C devices are supposed to support DAA (Dynamic Address Assignment), and
    > > +are thus discoverable. So, by default, I3C devices do not have to be described
    > > +in the device tree.
    > > +This being said, one might want to attach extra resources to these devices,
    > > +and those resources may have to be described in the device tree, which in turn
    > > +means we have to describe I3C devices.
    > > +
    > > +Another use case for describing an I3C device in the device tree is when this
    > > +I3C device has a static address and we want to assign it a specific dynamic
    > > +address before the DAA takes place (so that other devices on the bus can't
    >
    > static is I2C address and dynamic is an I3C address. That could be
    > clearer throughout.

    I'll clarify that.

    >
    > > +take this dynamic address).
    > > +
    > > +The I3C device should be names <device-type>@<static-address>,<i3c-pid>,
    >
    > s/static-address/static-i2c-address/

    Okay.

    >
    > > +where device-type is describing the type of device connected on the bus
    > > +(gpio-controller, sensor, ...).
    > > +
    > > +Required properties
    > > +-------------------
    > > +- reg: contains 3 cells
    > > + + first cell : encodes the I2C address. Should be 0 if the device does not
    > > + have one (0 is not a valid I3C address).
    >
    > Change here to "encodes the static I2C address".
    >
    > 0 is not a valid I2C address?

    According to [1] it is reserved, and it's reserved in the I3C spec
    anyway (see "Table 9 I3C Slave Address Restrictions" in the I3C spec).

    >
    > > +
    > > + + second and third cells: should encode the ProvisionalID. The second cell
    > > + contains the manufacturer ID left-shifted by 1.
    > > + The third cell contains ORing of the part ID
    > > + left-shifted by 16, the instance ID left-shifted
    > > + by 12 and the extra information. This encoding is
    > > + following the PID definition provided by the I3C
    > > + specification.

    One extra question for you: should I refer to the I3C_DEV(),
    I3C_DEV_WITH_STATIC_ADDR() and I2C_DEV() macros in the bindings doc?
    And if I do, should I use them my example?

    Thanks,

    Boris

    > > +
    > > +Optional properties
    > > +-------------------
    > > +- assigned-address: dynamic address to be assigned to this device. This
    > > + property is only valid if the I3C device has a static
    > > + address (first cell of the reg property != 0).
    > > +
    > > +
    > > +Example:
    > > +
    > > + i3c-master@d040000 {
    > > + compatible = "cdns,i3c-master";
    > > + clocks = <&coreclock>, <&i3csysclock>;
    > > + clock-names = "pclk", "sysclk";
    > > + interrupts = <3 0>;
    > > + reg = <0x0d040000 0x1000>;
    > > + #address-cells = <3>;
    > > + #size-cells = <0>;
    > > +
    > > + status = "okay";
    > > + i2c-scl-frequency = <100000>;
    > > +
    > > + /* I2C device. */
    > > + nunchuk: nunchuk@52 {
    > > + compatible = "nintendo,nunchuk";
    > > + reg = <0x52 0x80000010 0x0>;
    > > + };
    > > +
    > > + /* I3C device with a static address. */
    > > + thermal_sensor: sensor@68,39200144004 {
    > > + reg = <0x68 0x392 0x144004>;
    > > + assigned-address = <0xa>;
    > > + };
    > > +
    > > + /*
    > > + * I3C device without a static address but requiring resources
    > > + * described in the DT.
    > > + */
    > > + sensor@0,39200154004 {
    > > + reg = <0x0 0x392 0x154004>;
    > > + clocks = <&clock_provider 0>;
    > > + };
    > > + };
    > > +
    > > --
    > > 2.14.1
    > >

    [1]http://www.i2c-bus.org/addressing

    --
    Boris Brezillon, Bootlin (formerly Free Electrons)
    Embedded Linux and Kernel engineering
    https://bootlin.com

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