Version:  2.0.40 2.2.26 2.4.37 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1

Linux/Documentation/devicetree/bindings/media/video-interfaces.txt

  1 Common bindings for video receiver and transmitter interfaces
  2 
  3 General concept
  4 ---------------
  5 
  6 Video data pipelines usually consist of external devices, e.g. camera sensors,
  7 controlled over an I2C, SPI or UART bus, and SoC internal IP blocks, including
  8 video DMA engines and video data processors.
  9 
 10 SoC internal blocks are described by DT nodes, placed similarly to other SoC
 11 blocks.  External devices are represented as child nodes of their respective
 12 bus controller nodes, e.g. I2C.
 13 
 14 Data interfaces on all video devices are described by their child 'port' nodes.
 15 Configuration of a port depends on other devices participating in the data
 16 transfer and is described by 'endpoint' subnodes.
 17 
 18 device {
 19         ...
 20         ports {
 21                 #address-cells = <1>;
 22                 #size-cells = <0>;
 23 
 24                 port@0 {
 25                         ...
 26                         endpoint@0 { ... };
 27                         endpoint@1 { ... };
 28                 };
 29                 port@1 { ... };
 30         };
 31 };
 32 
 33 If a port can be configured to work with more than one remote device on the same
 34 bus, an 'endpoint' child node must be provided for each of them.  If more than
 35 one port is present in a device node or there is more than one endpoint at a
 36 port, or port node needs to be associated with a selected hardware interface,
 37 a common scheme using '#address-cells', '#size-cells' and 'reg' properties is
 38 used.
 39 
 40 All 'port' nodes can be grouped under optional 'ports' node, which allows to
 41 specify #address-cells, #size-cells properties independently for the 'port'
 42 and 'endpoint' nodes and any child device nodes a device might have.
 43 
 44 Two 'endpoint' nodes are linked with each other through their 'remote-endpoint'
 45 phandles.  An endpoint subnode of a device contains all properties needed for
 46 configuration of this device for data exchange with other device.  In most
 47 cases properties at the peer 'endpoint' nodes will be identical, however they
 48 might need to be different when there is any signal modifications on the bus
 49 between two devices, e.g. there are logic signal inverters on the lines.
 50 
 51 It is allowed for multiple endpoints at a port to be active simultaneously,
 52 where supported by a device.  For example, in case where a data interface of
 53 a device is partitioned into multiple data busses, e.g. 16-bit input port
 54 divided into two separate ITU-R BT.656 8-bit busses.  In such case bus-width
 55 and data-shift properties can be used to assign physical data lines to each
 56 endpoint node (logical bus).
 57 
 58 
 59 Required properties
 60 -------------------
 61 
 62 If there is more than one 'port' or more than one 'endpoint' node or 'reg'
 63 property is present in port and/or endpoint nodes the following properties
 64 are required in a relevant parent node:
 65 
 66  - #address-cells : number of cells required to define port/endpoint
 67                     identifier, should be 1.
 68  - #size-cells    : should be zero.
 69 
 70 Optional endpoint properties
 71 ----------------------------
 72 
 73 - remote-endpoint: phandle to an 'endpoint' subnode of a remote device node.
 74 - slave-mode: a boolean property indicating that the link is run in slave mode.
 75   The default when this property is not specified is master mode. In the slave
 76   mode horizontal and vertical synchronization signals are provided to the
 77   slave device (data source) by the master device (data sink). In the master
 78   mode the data source device is also the source of the synchronization signals.
 79 - bus-width: number of data lines actively used, valid for the parallel busses.
 80 - data-shift: on the parallel data busses, if bus-width is used to specify the
 81   number of data lines, data-shift can be used to specify which data lines are
 82   used, e.g. "bus-width=<8>; data-shift=<2>;" means, that lines 9:2 are used.
 83 - hsync-active: active state of the HSYNC signal, 0/1 for LOW/HIGH respectively.
 84 - vsync-active: active state of the VSYNC signal, 0/1 for LOW/HIGH respectively.
 85   Note, that if HSYNC and VSYNC polarities are not specified, embedded
 86   synchronization may be required, where supported.
 87 - data-active: similar to HSYNC and VSYNC, specifies data line polarity.
 88 - field-even-active: field signal level during the even field data transmission.
 89 - pclk-sample: sample data on rising (1) or falling (0) edge of the pixel clock
 90   signal.
 91 - sync-on-green-active: active state of Sync-on-green (SoG) signal, 0/1 for
 92   LOW/HIGH respectively.
 93 - data-lanes: an array of physical data lane indexes. Position of an entry
 94   determines the logical lane number, while the value of an entry indicates
 95   physical lane, e.g. for 2-lane MIPI CSI-2 bus we could have
 96   "data-lanes = <1 2>;", assuming the clock lane is on hardware lane 0.
 97   This property is valid for serial busses only (e.g. MIPI CSI-2).
 98 - clock-lanes: an array of physical clock lane indexes. Position of an entry
 99   determines the logical lane number, while the value of an entry indicates
100   physical lane, e.g. for a MIPI CSI-2 bus we could have "clock-lanes = <0>;",
101   which places the clock lane on hardware lane 0. This property is valid for
102   serial busses only (e.g. MIPI CSI-2). Note that for the MIPI CSI-2 bus this
103   array contains only one entry.
104 - clock-noncontinuous: a boolean property to allow MIPI CSI-2 non-continuous
105   clock mode.
106 - link-frequencies: Allowed data bus frequencies. For MIPI CSI-2, for
107   instance, this is the actual frequency of the bus, not bits per clock per
108   lane value. An array of 64-bit unsigned integers.
109 - lane-polarities: an array of polarities of the lanes starting from the clock
110   lane and followed by the data lanes in the same order as in data-lanes.
111   Valid values are 0 (normal) and 1 (inverted). The length of the array
112   should be the combined length of data-lanes and clock-lanes properties.
113   If the lane-polarities property is omitted, the value must be interpreted
114   as 0 (normal). This property is valid for serial busses only.
115 
116 
117 Example
118 -------
119 
120 The example snippet below describes two data pipelines.  ov772x and imx074 are
121 camera sensors with a parallel and serial (MIPI CSI-2) video bus respectively.
122 Both sensors are on the I2C control bus corresponding to the i2c0 controller
123 node.  ov772x sensor is linked directly to the ceu0 video host interface.
124 imx074 is linked to ceu0 through the MIPI CSI-2 receiver (csi2). ceu0 has a
125 (single) DMA engine writing captured data to memory.  ceu0 node has a single
126 'port' node which may indicate that at any time only one of the following data
127 pipelines can be active: ov772x -> ceu0 or imx074 -> csi2 -> ceu0.
128 
129         ceu0: ceu@0xfe910000 {
130                 compatible = "renesas,sh-mobile-ceu";
131                 reg = <0xfe910000 0xa0>;
132                 interrupts = <0x880>;
133 
134                 mclk: master_clock {
135                         compatible = "renesas,ceu-clock";
136                         #clock-cells = <1>;
137                         clock-frequency = <50000000>;   /* Max clock frequency */
138                         clock-output-names = "mclk";
139                 };
140 
141                 port {
142                         #address-cells = <1>;
143                         #size-cells = <0>;
144 
145                         /* Parallel bus endpoint */
146                         ceu0_1: endpoint@1 {
147                                 reg = <1>;              /* Local endpoint # */
148                                 remote = <&ov772x_1_1>; /* Remote phandle */
149                                 bus-width = <8>;        /* Used data lines */
150                                 data-shift = <2>;       /* Lines 9:2 are used */
151 
152                                 /* If hsync-active/vsync-active are missing,
153                                    embedded BT.656 sync is used */
154                                 hsync-active = <0>;     /* Active low */
155                                 vsync-active = <0>;     /* Active low */
156                                 data-active = <1>;      /* Active high */
157                                 pclk-sample = <1>;      /* Rising */
158                         };
159 
160                         /* MIPI CSI-2 bus endpoint */
161                         ceu0_0: endpoint@0 {
162                                 reg = <0>;
163                                 remote = <&csi2_2>;
164                         };
165                 };
166         };
167 
168         i2c0: i2c@0xfff20000 {
169                 ...
170                 ov772x_1: camera@0x21 {
171                         compatible = "ovti,ov772x";
172                         reg = <0x21>;
173                         vddio-supply = <&regulator1>;
174                         vddcore-supply = <&regulator2>;
175 
176                         clock-frequency = <20000000>;
177                         clocks = <&mclk 0>;
178                         clock-names = "xclk";
179 
180                         port {
181                                 /* With 1 endpoint per port no need for addresses. */
182                                 ov772x_1_1: endpoint {
183                                         bus-width = <8>;
184                                         remote-endpoint = <&ceu0_1>;
185                                         hsync-active = <1>;
186                                         vsync-active = <0>; /* Who came up with an
187                                                                inverter here ?... */
188                                         data-active = <1>;
189                                         pclk-sample = <1>;
190                                 };
191                         };
192                 };
193 
194                 imx074: camera@0x1a {
195                         compatible = "sony,imx074";
196                         reg = <0x1a>;
197                         vddio-supply = <&regulator1>;
198                         vddcore-supply = <&regulator2>;
199 
200                         clock-frequency = <30000000>;   /* Shared clock with ov772x_1 */
201                         clocks = <&mclk 0>;
202                         clock-names = "sysclk";         /* Assuming this is the
203                                                            name in the datasheet */
204                         port {
205                                 imx074_1: endpoint {
206                                         clock-lanes = <0>;
207                                         data-lanes = <1 2>;
208                                         remote-endpoint = <&csi2_1>;
209                                 };
210                         };
211                 };
212         };
213 
214         csi2: csi2@0xffc90000 {
215                 compatible = "renesas,sh-mobile-csi2";
216                 reg = <0xffc90000 0x1000>;
217                 interrupts = <0x17a0>;
218                 #address-cells = <1>;
219                 #size-cells = <0>;
220 
221                 port@1 {
222                         compatible = "renesas,csi2c";   /* One of CSI2I and CSI2C. */
223                         reg = <1>;                      /* CSI-2 PHY #1 of 2: PHY_S,
224                                                            PHY_M has port address 0,
225                                                            is unused. */
226                         csi2_1: endpoint {
227                                 clock-lanes = <0>;
228                                 data-lanes = <2 1>;
229                                 remote-endpoint = <&imx074_1>;
230                         };
231                 };
232                 port@2 {
233                         reg = <2>;                      /* port 2: link to the CEU */
234 
235                         csi2_2: endpoint {
236                                 remote-endpoint = <&ceu0_0>;
237                         };
238                 };
239         };

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us