Debian Sid Gnome does not boot into Desktop

Hi,
As I have successfully flashed the latest Linaro’s Debian boot and root filesystem images (gnome images) into my RB5, and from the console via the debug UART :
root@linaro-gnome:~# uname -ra
Linux linaro-gnome 5.12.0-qcomlt-arm64 #175 SMP PREEMPT Fri Apr 9 10:21:56 UTC 2021 aarch64 GNU/Linux
However, there’s nothing happen on the connected HDMI display. Is there any missing step during the installation or the HDMI has not been supported yet in this release, please ?

Similar result with Linaro Debian Sid Gnome 65.

Update : It seems that the board uses Lontium LT9611 mipi-dsi to hdmi converter. However, dmesg shows :
root@linaro-gnome:~# dmesg | grep dsi
[ 0.000000] Kernel command line: root=PARTLABEL=rootfs console=tty0 console=ttyMSM0,115200n8 pci:
[ 8.405621] msm_dsi ae94000.dsi: supply gdsc not found, using dummy regulator
[ 8.441640] msm_dsi_manager_register: failed to register mipi dsi host for DSI 0
[ 8.493717] msm_dsi ae94000.dsi: supply gdsc not found, using dummy regulator
[ 8.502922] msm_dsi_manager_register: failed to register mipi dsi host for DSI 0
[ 8.558711] msm_dsi ae94000.dsi: supply gdsc not found, using dummy regulator
[ 8.588552] msm_dsi_manager_register: failed to register mipi dsi host for DSI 0
[ 8.677091] msm_dsi ae94000.dsi: supply gdsc not found, using dummy regulator
[ 8.677961] msm_dsi_manager_register: failed to register mipi dsi host for DSI 0
[ 8.731044] msm_dsi ae94000.dsi: supply gdsc not found, using dummy regulator
[ 8.751145] msm_dsi_manager_register: failed to register mipi dsi host for DSI 0
[ 9.013107] msm_dsi ae94000.dsi: supply gdsc not found, using dummy regulator
[ 9.025528] msm ae00000.mdss: bound ae94000.dsi (ops dsi_ops [msm])

Thanks in advance,
K.