issue with LVDS display in imx8qxp

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issue with LVDS display in imx8qxp

5,382 Views
adnan_dst
Contributor III

Hi,

We are using imx8qxp with custom carrier board. We are using a G104STN010 display.
I am able to get display backlight and control it but there is not display output.

we are using custom OS with kernel version :- 6.6.36

dmesg logs show Failed to create device link (0x180) with 56180000.dpu

root@imx8qxpc0mek:~# dmesg | grep lvds
[    0.424742] platform lvds0_panel: Fixed dependency cycle(s) with /ldb1-display-controller/lvds-channel@0
[    2.927034] debugfs: Directory 'lvds1' with parent 'pm_genpd' already present!
root@imx8qxpc0mek:~# dmesg | grep ldb 
[    0.424742] platform lvds0_panel: Fixed dependency cycle(s) with /ldb1-display-controller/lvds-channel@0
[    1.403962] imx8qxp-ldb ldb1-display-controller: Failed to create device link (0x180) with 56180000.dpu
[    2.639559] imx8qxp-ldb ldb1-display-controller: Failed to create device link (0x180) with 56221000.ldb_phy

Below is my device tree configuration:-

lvds0_panel {
            compatible = "auo,g104stn01";
            status = "okay";
            /*backlight   = <&lvds_backlight0>;*/
            data-mapping = "jeida-18";  /* For 6-bit LVDS */
            width-mm = <211>;
            height-mm = <158>;
                pinctrl-names = "default";
                pinctrl-0 = <&pinctrl_lvds>;
                gpio = <&lsio_gpio0 26 GPIO_ACTIVE_HIGH
                        &lsio_gpio0 27 GPIO_ACTIVE_HIGH>;
    
    
            panel-timing {
                  clock-frequency = <40000000>;  /* 40 MHz pixel clock */
                  hactive = <800>;
                  vactive = <600>;
                  hback-porch = <88>;
                  hfront-porch = <40>;
                  vback-porch = <3>;
                  vfront-porch = <29>;
                  vsync-len = <6>;
                  hsync-len = <128>;
            };
 
            port {
                  panel_lvds_in: endpoint {
                     remote-endpoint = <&lvds_out>;
                  };
            };
      };
 
&ldb1_phy {
      status = "okay";
};
 
&ldb1 {
      status = "okay";
 
      lvds-channel@0 {
            fsl,data-mapping = "spwg";
            fsl,data-width = <18>; /* LVDS data input selection 6bits */
            status = "okay";
            
            port@1 {
                  reg = <1>;
 
                  lvds_out: endpoint {
                        remote-endpoint = <&panel_lvds_in>;
                  };
            };
      };
};

is my device tree configuration correct? or is there any changes to be done to bring up lvds diaplay.

Thanks,




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11 Replies

5,342 Views
Zhiming_Liu
NXP TechSupport
NXP TechSupport

Hello,

Please share the dts file in attachment.

Best Regards,
Zhiming

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5,326 Views
adnan_dst
Contributor III

Hello Zhiming,

I have attached the dtsi file which we are modifying please have a look.

Thanks,

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5,301 Views
Zhiming_Liu
NXP TechSupport
NXP TechSupport

Hello,

The ‘’Failed to create device link (0x180)' is a noisy log and not affect display.

Please share full kernel log.

Best Regards,
Zhiming

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5,288 Views
adnan_dst
Contributor III

Hello,

Below is the attached dmesg log. Please let me know if you need anything else..

Regards,
Adnan

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5,284 Views
Zhiming_Liu
NXP TechSupport
NXP TechSupport

Hello,

The driver can't parse pane-timing from dts.

You may need adjust the code indentation to solve this problem

Zhiming_Liu_0-1733290190419.png

 



Best Regards,
Zhiming

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5,273 Views
adnan_dst
Contributor III

Hello,

As you had suggested i have fixed the indentation issue in device tree i have attached the updated device tree and the dmesg complete log.

After fixing the indentation issue still we are facing the same issue we are able to get backlight but no gui display.

Best Regards,
Adnan

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5,228 Views
Zhiming_Liu
NXP TechSupport
NXP TechSupport

Hello,

From the log, it looks like the kernel has been reloading the camera driver repeatedly, causing the display driver to be reloaded as well. Please don't comment the camera related nodes and then see if you can display it. If it can be displayed, then delete the related nodes in the device tree and remove the related configurations in defconfig.

Best Regards,
Zhiming

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5,209 Views
adnan_dst
Contributor III

Hello,

After switching from lvds0_panel to panel_lvds, we successfully obtained LVDS output. However, the desktop colors appear different, and the date and time text is not displayed properly. I’ve attached the DTSI file and pictures of the LVDS output. Please advise on possible solutions.

Best Regards,
Adnan

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5,159 Views
Zhiming_Liu
NXP TechSupport
NXP TechSupport

Hello,

Can you confirm that the panel is set for 18bit, not 24bit?

Best Regards,
Zhiming

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5,077 Views
adnan_dst
Contributor III
Hello,

I just had confirmation from our team that it's indeed set to 18 bit.

Best Regards,
Adnan
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4,333 Views
Zhiming_Liu
NXP TechSupport
NXP TechSupport

Hello,

You can try another data format and see if that solves the problem.

Best Regards,
Zhiming

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