Re: [PATCH v9 4/5] arm64: dts: ti: k3-j784s4-evm: Enable DisplayPort-0

From: Jayesh Choudhary
Date: Mon Aug 07 2023 - 08:25:32 EST

Hello Aradhya,

Thank you for the review.

On 05/08/23 00:52, Aradhya Bhatia wrote:
Hi Jayesh,

On 03-Aug-23 13:34, Jayesh Choudhary wrote:
From: Rahul T R <r-ravikumar@xxxxxx>

Enable display for J784S4 EVM.

Add assigned clocks for DSS, DT node for DisplayPort PHY and pinmux for
DP HPD. Add the clock frequency for serdes_refclk.

Add the endpoint nodes to describe connection from:
DSS => MHDP => DisplayPort connector.

Also add the GPIO expander-4 node and pinmux for main_i2c4 which is
required for controlling DP power. Set status for all required nodes
for DP-0 as "okay".

Signed-off-by: Rahul T R <r-ravikumar@xxxxxx>
[j-choudhary@xxxxxx: move all the changes together to enable DP-0 in EVM]
Signed-off-by: Jayesh Choudhary <j-choudhary@xxxxxx>
arch/arm64/boot/dts/ti/k3-j784s4-evm.dts | 119 +++++++++++++++++++++++
1 file changed, 119 insertions(+)


+ reg = <0>;
+ cdns,num-lanes = <4>;
+ #phy-cells = <0>;
+ cdns,phy-type = <PHY_TYPE_DP>;
+ resets = <&serdes_wiz4 1>, <&serdes_wiz4 2>,
+ <&serdes_wiz4 3>, <&serdes_wiz4 4>;
+ };
+&mhdp {
+ status = "okay";
+ pinctrl-names = "default";
+ pinctrl-0 = <&dp0_pins_default>;
+ phys = <&serdes4_dp_link>;
+ phy-names = "dpphy";
+&dss_ports {
+ port {

Port index has not been added here. Since this port outputs to MHDP
bridge, this should be "port@0", and a "reg = <0>;" property should be
added below (along with the address and size cells properties).

I suppose this works functionally in this case, because the port gets
defaulted to "0" by the driver. But in future, when we add support for
other dss output(s) on j784s4-evm, the driver will need indices to
distinguish among them.

Okay. It makes sense.
Just one thing here. Adding reg here would require it to have #address-
cells and #size-cell but since we have only single child port that too
at reg=<0>, it would throw dtbs_check warning:

arch/arm64/boot/dts/ti/k3-j784s4-main.dtsi:1828.20-1831.5: Warning
(graph_child_address): /bus@100000/dss@4a00000/ports: graph node has
single child node 'port@0', #address-cells/#size-cells are not necessary
also defined at arch/arm64/boot/dts/ti/k3-j784s4-evm.dts:911.12-919.3


+ dpi0_out: endpoint {
+ remote-endpoint = <&dp0_in>;