Hi Archit,
Many thanks for this documentation add-on.
I wonder if an extra example of "2 DSI hosts driving a dual-channel DSI
peripheral controlled by the mipi bus" could be useful? well, I am not
really convinced it is necessary and maybe this extra example could be
added later when someone will meet the case... and I should have sent
this comment on v1 (sorry for the delay).
Reviewed-by: Philippe Cornu <philippe.cornu@xxxxxx>
Philippe :-)
On 01/18/2018 05:53 AM, Archit Taneja wrote:
> Add binding info for peripherals that support dual-channel DSI. Add
> corresponding optional bindings for DSI host controllers that may
> be configured in this mode. Add an example of an I2C controlled
> device operating in dual-channel DSI mode.
>
> Signed-off-by: Archit Taneja <architt@xxxxxxxxxxxxxx>
> ---
> v2:
> - Specify that clock-master is a boolean property.
> - Drop/add unit-address and #*-cells where applicable.
>
> .../devicetree/bindings/display/mipi-dsi-bus.txt | 80 ++++++++++++++++++++++
> 1 file changed, 80 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt b/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt
> index 94fb72cb916f..7a3abbedb3fa 100644
> --- a/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt
> +++ b/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt
> @@ -29,6 +29,13 @@ Required properties:
> - #size-cells: Should be 0. There are cases where it makes sense to use a
> different value here. See below.
>
> +Optional properties:
> +- clock-master: boolean. Should be enabled if the host is being used in
> + conjunction with another DSI host to drive the same peripheral. Hardware
> + supporting such a configuration generally requires the data on both the busses
> + to be driven by the same clock. Only the DSI host instance controlling this
> + clock should contain this property.
> +
> DSI peripheral
> ==============
>
> @@ -62,6 +69,16 @@ primary control bus, but are also connected to a DSI bus (mostly for the data
> path). Connections between such peripherals and a DSI host can be represented
> using the graph bindings [1], [2].
>
> +Peripherals that support dual channel DSI
> +-----------------------------------------
> +
> +Peripherals with higher bandwidth requirements can be connected to 2 DSI
> +busses. Each DSI bus/channel drives some portion of the pixel data (generally
> +left/right half of each line of the display, or even/odd lines of the display).
> +The graph bindings should be used to represent the multiple DSI busses that are
> +connected to this peripheral. Each DSI host's output endpoint can be linked to
> +an input endpoint of the DSI peripheral.
> +
> [1] Documentation/devicetree/bindings/graph.txt
> [2] Documentation/devicetree/bindings/media/video-interfaces.txt
>
> @@ -71,6 +88,8 @@ Examples
> with different virtual channel configurations.
> - (4) is an example of a peripheral on a I2C control bus connected with to
> a DSI host using of-graph bindings.
> +- (5) is an example of 2 DSI hosts driving a dual-channel DSI peripheral,
> + which uses I2C as its primary control bus.
>
> 1)
> dsi-host {
> @@ -153,3 +172,64 @@ Examples
> };
> };
> };
> +
> +5)
> + i2c-host {
> + dsi-bridge@35 {
> + compatible = "...";
> + reg = <0x35>;
> +
> + ports {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + port@0 {
> + reg = <0>;
> + dsi0_in: endpoint {
> + remote-endpoint = <&dsi0_out>;
> + };
> + };
> +
> + port@1 {
> + reg = <1>;
> + dsi1_in: endpoint {
> + remote-endpoint = <&dsi1_out>;
> + };
> + };
> + };
> + };
> + };
> +
> + dsi0-host {
> + ...
> +
> + /*
> + * this DSI instance drives the clock for both the host
> + * controllers
> + */
> + clock-master;
> +
> + ports {
> + ...
> +
> + port {
> + dsi0_out: endpoint {
> + remote-endpoint = <&dsi0_in>;
> + };
> + };
> + };
> + };
> +
> + dsi1-host {
> + ...
> +
> + ports {
> + ...
> +
> + port {
> + dsi1_out: endpoint {
> + remote-endpoint = <&dsi1_in>;
> + };
> + };
> + };
> + };
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