[Bug 41366] New: HDMI on a Fusion board only comes up when LVDS is already enabled

[bugzilla-daemon@freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=41366

           Summary: HDMI on a Fusion board only comes up when LVDS is
                    already enabled
           Product: DRI
           Version: XOrg CVS
          Platform: x86 (IA32)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/Radeon
        AssignedTo: dri-devel@lists.freedesktop.org
        ReportedBy: simon.farnsworth@onelan.co.uk


I'm running airlied's drm-fixes, git revision
fdfc61594e6de21c23f955818ef78bcab9bafe40, and experiencing "interesting" times
trying to get HDMI to work on a Fusion GPU (detected by X as [    49.876] (--)
RADEON(0): Chipset: "AMD Radeon HD 6310 Graphics" (ChipID = 0x9802)).

If I run:
xrandr --output HDMI-0 --off
xrandr --output LVDS --auto
xrandr --output HDMI-0 --mode 1920x1200

the HDMI monitor comes up at 1920x1200

If I run:
xrandr --output HDMI-0 --off
xrandr --output LVDS --off
xrandr --output HDMI-0 --mode 1920x1200

the HDMI monitor immediately enters DPMS Off state, and stays there.

I've confirmed with "grep . /sys/class/drm/card0-HDMI-A-1/*" that the kernel
thinks the HDMI connector is switched on. The only difference I can see is that
HDMI works when it gets CRTC 1, but not when it gets CRTC 0.

I have captured logs from the kernel with drm.debug=0x6 during the runs, in
case that explains what's going on; I will attach them to this bug.

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