1MIPI DSI (Display Serial Interface) busses
2==========================================
3
4The MIPI Display Serial Interface specifies a serial bus and a protocol for
5communication between a host and up to four peripherals. This document will
6define the syntax used to represent a DSI bus in a device tree.
7
8This document describes DSI bus-specific properties only or defines existing
9standard properties in the context of the DSI bus.
10
11Each DSI host provides a DSI bus. The DSI host controller's node contains a
12set of properties that characterize the bus. Child nodes describe individual
13peripherals on that bus.
14
15The following assumes that only a single peripheral is connected to a DSI
16host. Experience shows that this is true for the large majority of setups.
17
18DSI host
19--------
20
21In addition to the standard properties and those defined by the parent bus of
22a DSI host, the following properties apply to a node representing a DSI host.
23
24Required properties:
25- #address-cells: The number of cells required to represent an address on the
26  bus. DSI peripherals are addressed using a 2-bit virtual channel number, so
27  a maximum of 4 devices can be addressed on a single bus. Hence the value of
28  this property should be 1.
29- #size-cells: Should be 0. There are cases where it makes sense to use a
30  different value here. See below.
31
32DSI peripheral
33--------------
34
35Peripherals are represented as child nodes of the DSI host's node. Properties
36described here apply to all DSI peripherals, but individual bindings may want
37to define additional, device-specific properties.
38
39Required properties:
40- reg: The virtual channel number of a DSI peripheral. Must be in the range
41  from 0 to 3.
42
43Some DSI peripherals respond to more than a single virtual channel. In that
44case two alternative representations can be chosen:
45- The reg property can take multiple entries, one for each virtual channel
46  that the peripheral responds to.
47- If the virtual channels that a peripheral responds to are consecutive, the
48  #size-cells can be set to 1. The first cell of each entry in the reg
49  property is the number of the first virtual channel and the second cell is
50  the number of consecutive virtual channels.
51
52Example
53-------
54
55	dsi-host {
56		...
57
58		#address-cells = <1>;
59		#size-cells = <0>;
60
61		/* peripheral responds to virtual channel 0 */
62		peripheral@0 {
63			compatible = "...";
64			reg = <0>;
65		};
66
67		...
68	};
69
70	dsi-host {
71		...
72
73		#address-cells = <1>;
74		#size-cells = <0>;
75
76		/* peripheral responds to virtual channels 0 and 2 */
77		peripheral@0 {
78			compatible = "...";
79			reg = <0, 2>;
80		};
81
82		...
83	};
84
85	dsi-host {
86		...
87
88		#address-cells = <1>;
89		#size-cells = <1>;
90
91		/* peripheral responds to virtual channels 1, 2 and 3 */
92		peripheral@1 {
93			compatible = "...";
94			reg = <1 3>;
95		};
96
97		...
98	};
99