890GX/HD4290 dual display question

[droidhacker]

I think the pinouts are in the RS780 databooks:

http://developer.amd.com/documentation/guides/Pages/default.aspx

http://developer.amd.com/assets/45732_rs780e_ds_pub_3.10.pdf

RS880 should be pretty much the same.

Wow. I like those... Going to take me a little while to process it all properly, but definitely the kind of stuff I like.

Holy crap... I think that everything I need is actually connected... and that it just needs to be put into TMDS mode, which can be done by setting a register!!!!

I.e., the Cable Adapter Detect line is used to set some register in a way that flips it into TMDS mode. So the problem here is getting the signal to the video bios, but this isn't strictly necessary if the either the bios sets it into TMDS mode BY DEFAULT, or if some other mechanism is used to flip it into TMDS mode.

This is usually part of the video bios.

Now I just need to figure out WHAT REGISTER, and HOW TO SET IT.....

[nanonyme]

Btw, for some more docco, check http://www.x.org/docs/AMD/ (if r7xx-specific docs don't exist there, might assume r6xx ones work and curse if things blow up)

[nanonyme]

Never mind, the first link includes everything in xorg, it seems.

[droidhacker]

Interesting....
According to http://developer.amd.com/Assets/4329...r_pub_1.01.pdf (AMD RS780 Register Programming Requirements) p. 5-5 at the bottom, the VBIOS/Driver is responsible for DDI programming sequence.... i.e., is this something we can override in the DRIVER?

[agd5f]

The driver is already able to program the DP connector as either TMDS or DP. It does one or the other based on the type of monitor it detects as attached.

[droidhacker]

The driver is already able to program the DP connector as either TMDS or DP. It does one or the other based on the type of monitor it detects as attached.

Right... so how do we tell it TMDS when it can't detect it?

[agd5f]

What might be disconnected is the gpio lines needed for non-DP ddc.

[droidhacker]

Those are the same pins as AUX (A8 and B8). Isn't DP ddc over AUX? I.e., doesn't DP *require* AUX to be connected?

Assuming that DP does NOT need AUX, can DVI possibly work without ddc by handing it everything manually? Or is ddc required just to turn the monitor on?

[agd5f]

you'll have to hack the driver directly. Something like:

--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -998,6 +998,9 @@ static enum drm_connector_status radeon_dp_detect(struct drm_connector *connecto
}
}

+ radeon_dig_connector->dp_sink_type = CONNECTOR_OBJECT_ID_DUAL_LINK_DVI_D;
+ ret = connector_status_connected;
+
return ret;
}

[agd5f]

You'll have to manually add the mode you want with xrandr.