[RFC v2 1/2] dt-bindings: mipi-dsi: Add info about peripherals with non-DSI control bus

[Philippe CORNU]

Hi Archit,

Many thanks for this documentation update.

Reviewed-by: Philippe Cornu <philippe.cornu at st.com>

Philippe :-)

On 01/18/2018 05:53 AM, Archit Taneja wrote:
> Add a section that describes dt-bindings for peripherals that support
> MIPI DSI, but have a different bus as the primary control bus, or no
> control bus at all. Add an example for a peripheral with a non-DSI
> control bus.
> 
> Signed-off-by: Archit Taneja <architt at codeaurora.org>
> ---
> v2:
> - Mentioned what to do if peripheral has no control bus
> - Drop unit-address and #*-cells where applicable.
> 
>   .../devicetree/bindings/display/mipi-dsi-bus.txt   | 71 +++++++++++++++++++---
>   1 file changed, 64 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt b/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt
> index 973c27273772..94fb72cb916f 100644
> --- a/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt
> +++ b/Documentation/devicetree/bindings/display/mipi-dsi-bus.txt
> @@ -16,7 +16,7 @@ The following assumes that only a single peripheral is connected to a DSI
>   host. Experience shows that this is true for the large majority of setups.
>   
>   DSI host
> ---------
> +========
>   
>   In addition to the standard properties and those defined by the parent bus of
>   a DSI host, the following properties apply to a node representing a DSI host.
> @@ -30,11 +30,16 @@ Required properties:
>     different value here. See below.
>   
>   DSI peripheral
> ---------------
> +==============
>   
> -Peripherals are represented as child nodes of the DSI host's node. Properties
> -described here apply to all DSI peripherals, but individual bindings may want
> -to define additional, device-specific properties.
> +Peripherals with DSI as control bus, or no control bus
> +------------------------------------------------------
> +
> +Peripherals with the DSI bus as the primary control bus, or peripherals with
> +no control bus but use the DSI bus to transmit pixel data are represented
> +as child nodes of the DSI host's node. Properties described here apply to all
> +DSI peripherals, but individual bindings may want to define additional,
> +device-specific properties.
>   
>   Required properties:
>   - reg: The virtual channel number of a DSI peripheral. Must be in the range
> @@ -49,9 +54,25 @@ case two alternative representations can be chosen:
>     property is the number of the first virtual channel and the second cell is
>     the number of consecutive virtual channels.
>   
> -Example
> --------
> +Peripherals with a different control bus
> +----------------------------------------
> +
> +There are peripherals that have I2C/SPI (or some other non-DSI bus) as the
> +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].
> +
> +[1] Documentation/devicetree/bindings/graph.txt
> +[2] Documentation/devicetree/bindings/media/video-interfaces.txt
>   
> +Examples
> +========
> +- (1), (2) and (3) are examples of a DSI host and peripheral on the DSI bus
> +  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.
> +
> +1)
>   	dsi-host {
>   		...
>   
> @@ -67,6 +88,7 @@ Example
>   		...
>   	};
>   
> +2)
>   	dsi-host {
>   		...
>   
> @@ -82,6 +104,7 @@ Example
>   		...
>   	};
>   
> +3)
>   	dsi-host {
>   		...
>   
> @@ -96,3 +119,37 @@ Example
>   
>   		...
>   	};
> +
> +4)
> +	i2c-host {
> +		...
> +
> +		dsi-bridge at 35 {
> +			compatible = "...";
> +			reg = <0x35>;
> +
> +			ports {
> +				...
> +
> +				port {
> +					bridge_mipi_in: endpoint {
> +						remote-endpoint = <&host_mipi_out>;
> +					};
> +				};
> +			};
> +		};
> +	};
> +
> +	dsi-host {
> +		...
> +
> +		ports {
> +			...
> +
> +			port {
> +				host_mipi_out: endpoint {
> +					remote-endpoint = <&bridge_mipi_in>;
> +				};
> +			};
> +		};
> +	};
>