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890GX/HD4290 dual display question

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  • #61
    Originally posted by agd5f View Post
    I think the pinouts are in the RS780 databooks:
    http://developer.amd.com/documentati...s/default.aspx
    http://developer.amd.com/assets/4573...s_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.....

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    • #62
      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)

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      • #63
        Never mind, the first link includes everything in xorg, it seems.

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        • #64
          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?

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          • #65
            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.

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            • #66
              Originally posted by agd5f View Post
              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?

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              • #67
                What might be disconnected is the gpio lines needed for non-DP ddc.

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                • #68
                  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?

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                  • #69
                    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;
                    }

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                    • #70
                      You'll have to manually add the mode you want with xrandr.

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                      • #71
                        DP uses aux, non-DP uses plain i2c. IIRC, they both use the same pins on the connector, but I'm not sure if the oem wired the i2c gpios to the connector; they might have just wired the aux line.

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                        • #72
                          The document you linked about the 780 suggests that both actually use the same pins on the 780 itself and are configured to either i2c or aux depending on what is there, i.e. discovered through cable adapter detect and/or vbios... which means that if the aux line is connected, so must be the i2c...

                          See http://developer.amd.com/assets/4573...s_pub_3.10.pdf table 3-12 on page 3-11.


                          But yeah, that driver hack is definitely what I was getting at. Thank you very much for that. Tonight looks like another fun-filled evening of hacking

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                          • #73
                            Ah, indeed. I wonder if the oem hooked up the pins at all since neither fglrx nor the open source driver are able to get an EDID from any monitor (DP or otherwise) on that connector.

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                            • #74
                              Originally posted by agd5f View Post
                              Ah, indeed. I wonder if the oem hooked up the pins at all since neither fglrx nor the open source driver are able to get an EDID from any monitor (DP or otherwise) on that connector.
                              I have a crazy feeling that my active adapter is a POS. It ties the Cable Adapter Detect line to DP power return, i.e. high, so I have a feeling that it is some kind of weird hackish thing. An actual DP monitor is supposed to tie Cable Adapter Detect low.

                              In any case though, fglrx *does* claim to be finding a monitor and activating it... just that nothing comes out of it. Presumably because it is trying to activate a DP monitor when a DVI is actually present.

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                              • #75
                                Originally posted by droidhacker View Post
                                I have a crazy feeling that my active adapter is a POS. It ties the Cable Adapter Detect line to DP power return, i.e. high, so I have a feeling that it is some kind of weird hackish thing. An actual DP monitor is supposed to tie Cable Adapter Detect low.

                                In any case though, fglrx *does* claim to be finding a monitor and activating it... just that nothing comes out of it. Presumably because it is trying to activate a DP monitor when a DVI is actually present.
                                ... another thought has occurred to me regarding my active adapter. It may be trying to be smart -- only go active if a DVI-DL is connected, otherwise go passive.

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