With SDK 5.0.2, HDMI display works only if the cable is plugged after the boot. If it is plugged before, the system still boots, but there is no display.
The attached file shows the configuration, and this is working with SDK 4.6: tegra194-p2822-disp.dtsi (2.9 KB)
Because of the inverse polarity of HDMI detect pin, I don’t think that we see the display on the dev kit.
As this board and the DT configuration works on the SDK 4.6, there should be a change either somewhere else in DT or Ubuntu kernel. If you search the related dmesg log for the word “fail”, you will notice the display-related lines.
I already corrected an Ethernet and a USB issue (sourcing from the DT changes in the new SDK) but couldn’t fix this HDMI display problem.
According to of/base.c, the “okay” and “ok” strings are treated equally for the attribute “status”. When I changed from:
&headX { status = “okay”; …
to:
&headX { status = “ok”; …
in the tegra194-p2822-disp.dtsi file with SDK 5.0.2, everything worked OK like in SDK 4.6.
I searched whole open source codes in the L4T and couldn’t find a code in which these two strings handled differently. Would it be possible that they are handled differently inside the closed-source NVIDIA graphics driver?
Honestly, I don’t think that would fix this issue…
This issue is intermittent from the beginning. So if you test it more times, it may still happen. And 2nd display head is more easier to hit issue than 1st head.
The criteria to hit this issue is the NV boot logo must show during boot up stage and after entering kernel, it would intermittently crash.
If you disable the logo from printing, then this issue won’t happen either.