Commen=
t # 5
on bug 10553=
4
from Alex Deucher
(In reply to Christian K=C3=B6nig 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 comm=
ent #4)
> Thanks for replies. My monitor is DVI DL only.
>=20
> My old Haswell i5 4670 with HD4600 graphics was also single link DVI o=
nly
> (https://commun=
ities.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.
>=20
> Otherwise I find myself assuming that the hardware is capable of DL DV=
I,
> 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.
>=20
> I understand if AMD object to coding for something that hasn't been
> validated (I'd do the same myself). Would it be possible alternativel=
y to
> provide hints in log output or code comments or on a wiki somewhere, s=
uch
> 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.
>=20
> 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 hardw=
are
may not like 30 Hz refresh rates.=20=20
> 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 u=
p as
3 HDMI connectors and a DP connector. What physical connectors are actuall=
y on
the board?