How to cinfig display DP output lane number

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
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1

We use HDMI_DP1 to connect to lcd. We only use HDMI_DP1_TX0 and HDMI_DP1_TX1, and let the other two lanes HDMI_DP1_TX2 and HDMI_DP1_TX3 free or float.
How to config the first two and disable the other two?

3

Please configure nvidia,lanes under the dp-display node under your sor in your device tree.

4

Hi, WayneWWW
Can you specify which file and which parameter can change the lane number? We use sor1 as two lane DP output.

5

You can use dmesg |grep dts to know which dts file is in use first. And then trace the code of device tree.

6

Hi, WayneWWW
our dts file shows:

sor1 {
             ......   ......
		dp-display {
			compatible = "dp, display";
			status = "okay";
			nvidia,is_ext_dp_panel = <0x1>;
			nvidia,pc2-disabled;
			linux,phandle = <0x79>;
			phandle = <0x79>;

			disp-default-out {
				nvidia,out-type = <0x3>;
				nvidia,out-hotplug-state = <0x0>;
				nvidia,out-parent-clk = "plld2";
				nvidia,out-xres = <0x1000>;
				nvidia,out-yres = <0x870>;
			};
                     ...... ......

         

             Can you help which parameter above is related to DP lane number?
7

Just add nvidia,lanes = <2> under your dp-display.

8

Hi，WayneWWW：
I delete the following:
//&sor1 {
// nvidia,typec-port = /bits/ 8 <1>;
//};
and add the following in tegra194-p2888-0001-p2822-0000-common.dtsi
&sor1 {
dp-display {
nvidia,lanes = <2>;
};
};

then, I can not measure DP AUX signal or DP signal on oscilloscope. Type-c controller is removed from our hardware design. Xavier DP port is connected directly to display device.
What else should I do to enable DP output?

9

Share your dmesg please.

10

dp.txt (93.5 KB)

Hi, WayneWWW
The attachment dp.txt is the dmesg log

11

Hi,

Please remove nvdisplays which are not in use on your board. And only leave the dp port you are using and share the dmesg again.

12

Hi, WayneWWW

13

dp-2.TXT (65.3 KB)

dp-2.txt is the log in which  nvdisplays were removed.
14

…I mean disable nvdisplay that are not in use… Not disable every nvdisplay…

15

dp-3.TXT (83.8 KB)
dp-3.txt is the log in which only dp nvdisplay is remained.

16

Pleas also sharethe schematic of the DP port part.

17

image
image742×263 7.08 KB

18

Also need to connector part.

19

Please also convert your dtb back to dts and attach it here.

20

image

21

Hi,

Is your power supply a 3.3v one? Because our DP driver is using 3.3v. Please follow the design guide document.

image
image1438×892 177 KB