Display is not comming up when resolution is 1920x1080


We are using Linux 4.14 kernel. When we set the display resolution to 1920x1080 (video=HDMI-A-1:1920x1080@60 ) display is not coming up, works only for 1280x720 (video=HDMI-A-1:1280x720@60 ).
Please help me to get this work.

1920x1080 is the default mode. You don’t have to specify the resolution if that is what you are after.

Your monitor is probably less sensitive to the hikey960’s timing irregularities at 1280x720 than it is at 1920x1080, or possibly the lower resolution has timing that is closer to spec.

There is nothing you can do to make that monitor work on the hikey960 short of reprogramming the monitor itself to be less sensitive. The SoC used on the hikey960 does NOT have an HDMI output port. The HDMI port is driven by a DSI to HDMI bridge. Even still, it is restricted to clocks that the SoC is able to generate, which being a non-HDMI device, do not conform to HDMI requirements.

Your best option will be to try different monitors until you find one that can cope with the peculiarities of this board.

Thanks for the response doitright.

We tried Linux-4.9 kernel and 1920x1080 is working here, but i am not sure what is the problem with 4.14 Kernel.

@leo-yan IIRC, you did mentioned some issue regarding HDMI with 4.14 kernel. Is it related to this issue?

Hi guys,

Before I encountered one issue is there have comparability issue for DRM drivers with different kernel versions.

If you are using kernel 4.9 and build AOSP with this kernel version, it will build based on old display interface; If fetch images from the snapshot folder [1], it’s only 4.9 compatible and cannot display HDMI with 4.14 kernel. Only if use kernel 4.14 and build AOSP with TARGET_KERNEL_USE=4.14 then we will get the drm_hwcomposer enabled.

So this means now the Android user land images cannot support the 4.9 and 4.14 kernel at the same time for display; you must build the AOSP respectively.

Another thing is important that after build the images, you must re-flash vendor.img, it has some dependency in this image for display.

@sumit.garg thanks for reminding.

[1] https://snapshots.linaro.org/96boards/hikey960/linaro/aosp-master/latest/