No Output on HDMI Signal for IMX8MP

[bc_th]

Hi everyone,

my team and I are using a 7" display from Actron (Model No. ETML070023UDRA, Resolution 800x480@60) and a Phytec i.MX8MP board running a Yocto system (Yogurt Vendor xwayland (Phytec Vendor Distribution) BSP-Yocto-FSL-i.MX8MP-PD21.1.3).

The display works fine when we plug it in on a laptop and the board also correctly displays output on our monitors (benq) but when we connect the display with the board it does not react at all.

xrandr and xrandr --listmonitors only prints "Can't open Display"

We've also tried setting the mode within the /etc/xdg/weston/weston.ini file and restarting weston/ the board but that did not have any effect either.

[output]
name=HDMI-A-1
mode=800x480

Another idea we tried is updating the u-boot environment via:

env set video HDMI-A-1:800x640M@60D
env save
boot

But that did not have any effect on the system. We also tried different options like the following with no luck either.

env set video mxcfb0,dev=hdmi,800x480@60,if=RGB24

Does anyone have any ideas what we missed or what we can try? We can also provide further information if needed. Thanks in advance!

[bc_th]

We fixed the issue. The default mode line that we got from connecting the display to the board was incorrect.
We created a mode with

cvt 800 480 60

and then put the whole resulting String into the weston.ini so it looks like this:

[output]
name=HDMI-A-1
mode=29.50  800 824 896 992  480 483 493 500 -hsync +vsync

 After a restart the board could interact with the display via HDMI.

Thanks for the previous help!

[joanxie]

pls share the logfile and give me the result when you use command dmesg | grep drm

[bc_th]

This is the log you mentioned

[    4.062709] imx-drm display-subsystem: trying to bring up master
[    4.062714] imx-drm display-subsystem: Looking for component 0
[    4.062721] imx-drm display-subsystem: Looking for component 1
[    4.062732] imx-drm display-subsystem: found component imx-lcdifv3-crtc.1, duplicate 0
[    4.062739] imx-drm display-subsystem: Looking for component 2
[    4.062745] imx-drm display-subsystem: Looking for component 3
[    4.062879] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[    4.069525] [drm] No driver support for vblank timestamp query.
[    4.075490] imx-drm display-subsystem: binding imx-lcdifv3-crtc.0 (ops lcdifv3_crtc_ops)
[    4.075538] imx-drm display-subsystem: bound imx-lcdifv3-crtc.0 (ops lcdifv3_crtc_ops)
[    4.083489] imx-drm display-subsystem: binding imx-lcdifv3-crtc.1 (ops lcdifv3_crtc_ops)
[    4.083556] imx-drm display-subsystem: bound imx-lcdifv3-crtc.1 (ops lcdifv3_crtc_ops)
[    4.091511] imx-drm display-subsystem: binding 32c00000.bus:ldb@32ec005c (ops imx8mp_ldb_ops)
[    4.098185] imx-drm display-subsystem: bound 32c00000.bus:ldb@32ec005c (ops imx8mp_ldb_ops)
[    4.106620] imx-drm display-subsystem: binding 32fd8000.hdmi (ops dw_hdmi_imx_ops)
[    4.126191] imx-drm display-subsystem: bound 32fd8000.hdmi (ops dw_hdmi_imx_ops)
[    4.134412] [drm] Initialized imx-drm 1.0.0 20120507 for display-subsystem on minor 1
[    4.525235] imx-drm display-subsystem: HDMI-A-1: EDID is invalid:
[    4.706411] imx-drm display-subsystem: fb0: imx-drmdrmfb frame buffer device

[joanxie]

did you use nxp bsp or your own SW? refer to your logfile:

imx-drm display-subsystem: HDMI-A-1: EDID is invalid:

for HDMI, you don't need add this in the uboot, pls share dtb file you use and tell me what pixel clock of your HDMI you use