On 05/18/2017 08:25 PM, Laurent Pinchart wrote:
Hi Archit,
On Thursday 18 May 2017 13:56:19 Archit Taneja wrote:
On 05/17/2017 12:16 AM, Eric Anholt wrote:
[snip]
In terms of physical connections:
[15-pin "DSI" connector on 2835]
| I2C | DSI
/ \ SPI |
[TS] [Atmel]------[TC358762]
\ |
\PWM |
\ | DPI
[some backlight]------[some unknown panel]
The binding I'm trying to create is to expose what's necessary for a
driver that talks I2C to the Atmel, which then controls the PWM and does
the command sequence over SPI to the Toshiba that sets up its end of the
DSI link.
The bridge (Atmel + TC358762 combination) here looks like it's primarily
an i2c device (i.e, the control bus is i2c). Therefore, the drm-bridge
driver here should be an i2c driver instead of a mipi_dsi_driver.
Glad to see we agree, that's what I've proposed in a separate answer :-) I'd
go one step further though, there should be no DRM bridge, just a DRM panel.
If the PCB containing the controller chips and the panel are part of a single
casing, and the set up won't work with another panel, then yeah, I agree. If the
bridge chips are on a separate adapter board, and there is a possibility to connect
other panels, then maybe a separate DRM bridge and a DRM panel might be a safer bet.
Thanks,
Archit
We have the facility to create a mipi DSI device without the need to have
a corresponding node in DT. The ADV7533 and TC358767 drivers are examples
of that.
The following is what the binding could look like, it's same as what Rob
also mentioned previously in the thread.
Thanks,
Archit
dsi1: dsi@7e700000 {
#address-cells = <1>;
#size-cells = <0>;
<...>
/* The SoC's DSI input/output port */
ports {
#address-cells = <1>;
#size-cells = <0>;
/* port@0 if needed */
port@1 {
dsi_out_port: endpoint {
reg = <1>;
remote-endpoint = <&bridge_dsi_port>;
};
};
};
};
i2c_dsi: i2c {
compatible = "i2c-gpio";
#address-cells = <1>;
#size-cells = <0>;
gpios = <&gpio 28 0
&gpio 29 0>;
/* the Atmel + TC35872 bridge */
pitouchscreen_bridge: bridge@45 {
This should thus be lcd@45.
compatible = "raspberrypi,touchscreen-bridge";
And this raspberrypi,7inch-touchscreen-panel. Shame we haven't standardized
the vendor name prefix to rpi :-/
reg = <0x45>;
ports {
#address-cells = <1>;
#size-cells = <0>;
port@0 {
reg = <0>;
bridge_dsi_port: endpoint {
This should be named panel_dsi_port.
remote-endpoint = <&dsi_out_port>;
};
};
port@1 {
reg = <1>;
bridge_dpi_port: endpoint {
remote-endpoint =
<&pitouchscreen_panel_port>;
};
};
The second port is thus not needed.
};
So we can simplify this to
port {
panel_dsi_port: endpoint {
remote-endpoint = <&dsi_out_port>;
};
};
(no need for a ports node when there's a single port)
};
};
lcd {
compatible = "raspberrypi,7inch-touchscreen-panel";
ports {
#address-cells = <1>;
#size-cells = <0>;
port@0 {
reg = <0>;
pitouchscreen_panel_port: endpoint {
remote-endpoint = <&bridge_dpi_port>;
};
};
};
};
And this node can go away.
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