[mythtv-users] Weird HDMI problem

[Lawrence Rust]

On Tue, 2012-04-03 at 14:34 +1000, Igor Cicimov wrote:
> Hi all,
> 
> 
> I have Mythtv 0.23 running on Mythbuntu 10.04 XFCE. The box is
> connected to Sony HD TV via HDMI cable and the graphics is ATI HD3200
> integrated one. My problem is with HDMI output, or I think it is since
> I can't find any other explanation. When I switch on the TV first and
> then the Mythtv all is fine. But the other way around I get a black
> screen.

This is almost certainly the ATI radeon driver disabling any
disconnected outputs.  I had the same problem with an analog TV
connected to TVout.  I fixed it by adding this to xorg.conf:

Section "Device"
	# copy existing
	....
	Option		"ForceTVOut" "on"
	# The above is documented for the radeon driver
	# For fglrx use:
	Option 		"NoTV" "no"     
EndSection

If this doesn't work then add this to /etc/rc.local

sudo xrandr --output HDMI1 --auto
(Replace HDMI! with the name of your HDMI output found by running xrandr
without any args)

The display should be connected when this is executed or the output will
be disabled.

If you're using the fglrx (Catalyst) driver then try aticonfig and
search for output options.

>  Same happens if I leave the Mythtv box idle for some time: when I
> switch back to it I get black screen. It is like due to some power
> savings, I assume on the TV side, the HDMI gets switched off. The only
> way to fix this is to unplug the HDMI cable from the TV and plug it
> back in (sometimes it takes couple of tries).

I found it best to disable DPMS power saving in xorg.conf:

Section "ServerFlags"
	Option	    "BlankTime" "0"  # default 10 mins
	Option	    "StandbyTime" "0"  # DPMS standby, default 10 mins
	Option	    "SuspendTime" "0"  # DPMS suspend, default 10 mins
	Option	    "OffTime" "0"  # DPMS off, default 10 mins
EndSection

> I tried connecting keyboard and mouse to try to wake up but it didn't
> work. They work but the screen is left black which makes me think it
> is definitely HDMI input/output problem. I also have the screen saver
> turned off on the box.

Try re-enabling the output with:

xrandr --output HDMI1 --auto

>  I've tried switching off dpms too but that didn't help either. I
> guess the HDMI output is turned off and the box can't read the EDID
> from the TV. Is it the ATI driver doing this or the TV I wonder?

I'll bet this is the ATI driver preferring the VGA output.

[snip]

-- 
Lawrence