https://bugs.freedesktop.org/show_bug.cgi?id=105534
--- Comment #5 from Alex Deucher alexdeucher@gmail.com --- (In reply to Christian König from comment #3)
What you can use is either an active DP to dual DVI converter (probably rather expensive if such a thing even exists) or native DP/HDMI (if the monitor has connectors for that).
They are actually relatively common for just these sorts of scenarios. Not sure about cost however.
(In reply to philipmorant from comment #4)
Thanks for replies. My monitor is DVI DL only.
My old Haswell i5 4670 with HD4600 graphics was also single link DVI only (https://communities.intel.com/thread/44135), and it worked at 60Hz. Could somebody please explain why haswell can do it but raven can't ?
I'm not sure how the intel hw is designed. I can't comment on exactly what is happening. I suspect what is happening is that the intel driver is not validating the link requirements and treating the DVI port like HDMI and sending the high bandwidth mode over a single TMDS link. The monitor just happens to accept it.
Otherwise I find myself assuming that the hardware is capable of DL DVI, just that the manufacturers aren't validating for it, ergo fixable in software.
No. DL DVI requires two digital transmitters, one for each TMDS link. We only wire a single transmitter to each physical connector. For DL DVI, you need two transmitters connected to the physical connector.
I understand if AMD object to coding for something that hasn't been validated (I'd do the same myself). Would it be possible alternatively to provide hints in log output or code comments or on a wiki somewhere, such that people in my position can hack the source themselves ?
You could try hacking the driver to treat the monitor as HDMI even through it's DL DVI. Maybe your monitor will accept the timing over a single TMDS link.
Secondly, even accepting the single link limitation, shouldn't it be possible to run at 33 refresh rate ? I tried at 30 and got nothing.
It depends on the hardware and the panel in the monitor. The monitor hardware may not like 30 Hz refresh rates.
Thirdly, why does amdgpu refer to the connection as HDMI-A-3 ? There's no HDMI in the setup at all.
The display connectors are read from a table in the bios and are determined by the OEM that designs the board. It our case the OEM seems to have set it up as 3 HDMI connectors and a DP connector. What physical connectors are actually on the board?