On Thu January 3 2013 18:03:49 Sylwester Nawrocki wrote:
> From: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
>
> This patch adds a document describing common OF bindings for video
> capture, output and video processing devices. It is curently mainly
> focused on video capture devices, with data busses defined by
> standards like ITU-R BT.656 or MIPI-CSI2.
> It also documents a method of describing data links between devices.
>
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> Signed-off-by: Sylwester Nawrocki <s.nawrocki@xxxxxxxxxxx>
> Reviewed-by: Stephen Warren <swarren@xxxxxxxxxx>
> Acked-by: Rob Herring <rob.herring@xxxxxxxxxxx>
As promised, here is my review:
> ---
>
> Changes since v2:
>
> - corrected pclk-sample property definition,
> - s/buses/busses,
> - whitespace changes.
>
> .../devicetree/bindings/media/video-interfaces.txt | 199 ++++++++++++++++++++
> 1 file changed, 199 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/media/video-interfaces.txt
>
> diff --git a/Documentation/devicetree/bindings/media/video-interfaces.txt b/Documentation/devicetree/bindings/media/video-interfaces.txt
> new file mode 100644
> index 0000000..9e9e95a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/video-interfaces.txt
> @@ -0,1 +1,199 @@
> +Common bindings for video data receiver and transmitter interfaces
> +
> +General concept
> +---------------
> +
> +Video data pipelines usually consist of external devices, e.g. camera sensors,
> +controlled over an I2C, SPI or UART bus, and SoC internal IP blocks, including
> +video DMA engines and video data processors.
> +
> +SoC internal blocks are described by DT nodes, placed similarly to other SoC
> +blocks. External devices are represented as child nodes of their respective
> +bus controller nodes, e.g. I2C.
> +
> +Data interfaces on all video devices are described by their child 'port' nodes.
> +Configuration of a port depends on other devices participating in the data
> +transfer and is described by 'endpoint' subnodes.
> +
> +dev {
> + #address-cells = <1>;
> + #size-cells = <0>;
> + port@0 {
> + endpoint@0 { ... };
> + endpoint@1 { ... };
> + };
> + port@1 { ... };
> +};
> +
> +If a port can be configured to work with more than one other device on the same
> +bus, an 'endpoint' child node must be provided for each of them. If more than
> +one port is present in a device node or there is more than one endpoint at a
> +port, a common scheme, using '#address-cells', '#size-cells' and 'reg' properties
> +is used.
> +
> +Two 'endpoint' nodes are linked with each other through their 'remote-endpoint'
> +phandles. An endpoint subnode of a device contains all properties needed for
> +configuration of this device for data exchange with the other device. In most
> +cases properties at the peer 'endpoint' nodes will be identical, however
> +they might need to be different when there is any signal modifications on the
> +bus between two devices, e.g. there are logic signal inverters on the lines.
> +
> +Required properties
> +-------------------
> +
> +If there is more than one 'port' or more than one 'endpoint' node following
> +properties are required in relevant parent node:
> +
> +- #address-cells : number of cells required to define port number, should be 1.
> +- #size-cells : should be zero.
> +
> +Optional endpoint properties
> +----------------------------
> +
> +- remote-endpoint: phandle to an 'endpoint' subnode of the other device node.
> +- slave-mode: a boolean property, run the link in slave mode. Default is master
> + mode.
> +- bus-width: number of data lines, valid for parallel busses.
> +- data-shift: on parallel data busses, if bus-width is used to specify the
> + number of data lines, data-shift can be used to specify which data lines are
> + used, e.g. "bus-width=<10>; data-shift=<2>;" means, that lines 9:2 are used.
> +- hsync-active: active state of HSYNC signal, 0/1 for LOW/HIGH respectively.
> +- vsync-active: active state of VSYNC signal, 0/1 for LOW/HIGH respectively.
> + Note, that if HSYNC and VSYNC polarities are not specified, embedded
> + synchronization may be required, where supported.
> +- data-active: similar to HSYNC and VSYNC, specifies data line polarity.
> +- field-even-active: field signal level during the even field data transmission.
> +- pclk-sample: sample data on rising (1) or falling (0) edge of the pixel clock
> + signal.
> +- data-lanes: an array of physical data lane indexes. Position of an entry
> + determines logical lane number, while the value of an entry indicates physical
> + lane, e.g. for 2-lane MIPI CSI-2 bus we could have "data-lanes = <1>, <2>;",
> + assuming the clock lane is on hardware lane 0. This property is valid for
> + serial busses only (e.g. MIPI CSI-2).
> +- clock-lanes: a number of physical lane used as a clock lane.
This doesn't parse. Do you mean:
"a number of physical lanes used as clock lanes."?
> +- clock-noncontinuous: a boolean property to allow MIPI CSI-2 non-continuous
> + clock mode.
> +
> +Example
> +-------
> +
> +The below example snippet describes two data pipelines. ov772x and imx074 are
s/below example snippet/example snippet below/
> +camera sensors with parallel and serial (MIPI CSI-2) video bus respectively.
s/with/with a/
> +Both sensors are on I2C control bus corresponding to i2c0 controller node.
s/on/on the/
s/to/to the/
> +ov772x sensor is linked directly to the ceu0 video host interface. imx074 is
> +linked to ceu0 through MIPI CSI-2 receiver (csi2). ceu0 has a (single) DMA
s/through/through the/
> +engine writing captured data to memory. ceu0 node has single 'port' node which
s/single/a single/
> +indicates at any time only one of following data pipeline can be active:
s/at/that at/
s/one of/one of the/
s/pipeline/pipelines/
> +ov772x -> ceu0 or imx074 -> csi2 -> ceu0.
> +
> + ceu0: ceu@0xfe910000 {
> + compatible = "renesas,sh-mobile-ceu";
> + reg = <0xfe910000 0xa0>;
> + interrupts = <0x880>;
> +
> + mclk: master_clock {
> + compatible = "renesas,ceu-clock";
> + #clock-cells = <1>;
> + clock-frequency = <50000000>; /* Max clock frequency */
> + clock-output-names = "mclk";
> + };
> +
> + port {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + ceu0_1: endpoint@1 {
> + reg = <1>; /* Local endpoint # */
> + remote = <&ov772x_1_1>; /* Remote phandle */
> + bus-width = <8>; /* Used data lines */
> + data-shift = <0>; /* Lines 7:0 are used */
> +
> + /* If hsync-active/vsync-active are missing,
> + embedded bt.605 sync is used */
> + hsync-active = <1>; /* Active high */
> + vsync-active = <1>; /* Active high */
> + data-active = <1>; /* Active high */
> + pclk-sample = <1>; /* Rising */
> + };
> +
> + ceu0_0: endpoint@0 {
> + reg = <0>;
> + remote = <&csi2_2>;
> + immutable;
> + };
> + };
> + };
> +
> + i2c0: i2c@0xfff20000 {
> + ...
> + ov772x_1: camera@0x21 {
> + compatible = "omnivision,ov772x";
> + reg = <0x21>;
> + vddio-supply = <®ulator1>;
> + vddcore-supply = <®ulator2>;
> +
> + clock-frequency = <20000000>;
> + clocks = <&mclk 0>;
> + clock-names = "xclk";
> +
> + port {
> + /* With 1 endpoint per port no need in addresses. */
> + ov772x_1_1: endpoint {
> + bus-width = <8>;
> + remote-endpoint = <&ceu0_1>;
> + hsync-active = <1>;
> + vsync-active = <0>; /* Who came up with an
> + inverter here ?... */
> + data-active = <1>;
> + pclk-sample = <1>;
> + };
> + };
> + };
> +
> + imx074: camera@0x1a {
> + compatible = "sony,imx074";
> + reg = <0x1a>;
> + vddio-supply = <®ulator1>;
> + vddcore-supply = <®ulator2>;
> +
> + clock-frequency = <30000000>; /* Shared clock with ov772x_1 */
> + clocks = <&mclk 0>;
> + clock-names = "sysclk"; /* Assuming this is the
> + name in the datasheet */
> + port {
> + imx074_1: endpoint {
> + clock-lanes = <0>;
> + data-lanes = <1>, <2>;
> + remote-endpoint = <&csi2_1>;
> + };
> + };
> + };
> + };
> +
> + csi2: csi2@0xffc90000 {
> + compatible = "renesas,sh-mobile-csi2";
> + reg = <0xffc90000 0x1000>;
> + interrupts = <0x17a0>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + port@1 {
> + compatible = "renesas,csi2c"; /* One of CSI2I and CSI2C. */
> + reg = <1>; /* CSI-2 PHY #1 of 2: PHY_S,
> + PHY_M has port address 0,
> + is unused. */
> + csi2_1: endpoint {
> + clock-lanes = <0>;
> + data-lanes = <2>, <1>;
> + remote-endpoint = <&imx074_1>;
> + };
> + };
> + port@2 {
> + reg = <2>; /* port 2: link to the CEU */
> +
> + csi2_2: endpoint {
> + immutable;
> + remote-endpoint = <&ceu0_0>;
> + };
> + };
> + };
Regards,
Hans
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