Need Help Enabling HDMI on Debix Model A

[Tarang Raval]

Hi Laurent,

I’m trying to bring up HDMI on the Debix Model A board using the
mainline kernel, but I’m currently facing issues.

I saw that you tested the patch for HDMI support on this board in
mainline, so I am hoping you could help me figure out what might be
missing.

To clarify — I'm using the prebuilt image provided by Debix, but I replaced
the kernel image and the device tree (DTS) file in the /boot directory with
ones built from the mainline kernel.

I’ve enabled the following configurations in the kernel:
CONFIG_DRM_DISPLAY_CONNECTOR=y
CONFIG_DRM_IMX8MP_DW_HDMI_BRIDGE=y
CONFIG_DRM_IMX8MP_HDMI_PVI=y
CONFIG_DRM_IMX_LCDIF=y
CONFIG_PHY_FSL_SAMSUNG_HDMI_PHY=y

When I boot the board, I see the following HDMI/DRM related logs:
debix at imx8mp-debix:~$ dmesg | grep -iE "drm|hdmi"
[    0.121979] /soc at 0/bus at 32c00000/display-bridge at 32fc4000: Fixed dependency cycle(s) with /soc at 0/bus at 32c00000/hdmi at 32fd8000
[    0.122164] /soc at 0/bus at 32c00000/hdmi at 32fd8000: Fixed dependency cycle(s) with /soc at 0/bus at 32c00000/display-bridge at 32fc4000
[    0.127417] /soc at 0/bus at 32c00000/hdmi at 32fd8000: Fixed dependency cycle(s) with /hdmi-connector
[    0.127608] /hdmi-connector: Fixed dependency cycle(s) with /soc at 0/bus at 32c00000/hdmi at 32fd8000
[    1.947962] imx8mp-dw-hdmi-tx 32fd8000.hdmi: Detected HDMI TX controller v2.13a with HDCP (SAMSUNG HDMI TX PHY)
[    1.949220] imx8mp-dw-hdmi-tx 32fd8000.hdmi: registered DesignWare HDMI I2C bus driver
[    1.956365] [drm] Initialized imx-lcdif 1.0.0 for 32fc6000.display-controller on minor 0
[    2.016601] imx-lcdif 32fc6000.display-controller: [drm] fb0: imx-lcdifdrmfb frame buffer device
[    8.380915] systemd[1]: Starting Load Kernel Module drm...


I also checked that the display's modeline is recognized under sysfs :

root at imx8mp-debix:~# ls /sys/class/drm/card0-HDMI-A-1/
connector_id  dpms          modes         subsystem/   
ddc/          edid          power/        uevent       
device/       enabled       status       

However, there is still no HDMI output on the display. Instead,
I only see a white blinking cursor on the screen.. I'm not sure
what I'm missing.

Could you please help me out or point me in the right direction?

Thank you for your time.

Best Regards,
Tarang