Bug 36516

Summary:

Problem with both VGA and HDMI active.

Product:

xorg

Reporter:

Joseph Farmer <jfarmer99>

Component:

Driver/Radeon

Assignee:

xf86-video-ati maintainers <xorg-driver-ati>

Status:

RESOLVED NOTOURBUG

QA Contact:

Xorg Project Team <xorg-team>

Severity:

normal

Priority:

medium

Version:

unspecified

Hardware:

Other

OS:

All

Whiteboard:

i915 platform:

i915 features:

Attachments:

Description	Flags
dmesg_vgaonly	none
xorg log vgaonly	none
dmesg_tvonly	none
xorg tvonly	none
dmesg_both	none
dmesg_both	none
xorg both	none
dmesg_hd5450_instead	none
xorg_hd5450_instead_with_both	none

Description Joseph Farmer 2011-04-22 18:22:19 UTC

Originally I had this computer connected, via VGA and DVI, to two monitors. It worked fine with those two monitors in the following configurations:
VGA/DVI
DVI/HDMI
HDMI/DVI
I could even disable VGA and enable HDMI to get a third monitor working at the expense of the second (42" TV on HDMI).

I have moved it and connected it to two monitors - Dell E1910H (VGA only) and a Westinghouse 42" LCD TV (HDMI only).  The follow is observed:

Boot with both plugged in results in a spew of EDID errors and no TV.  HDMI cannot be enabled.  VGA works fine.

Boot with only TV plugged in and it works fine - EDID is correct.

Then plug in the VGA (after booting with HDMI working).  Using xrandr activate the VGA:
xrandr --output VGA-0 --auto
and the VGA comes up but the HDMI disconnects.

So I know the HDMI connector, cable, and TV are fine as that works if I boot with only that plugged in.  Plugging in the VGA ensures the HDMI doesn't work but the VGA comes up.

Strange given the card was able to do that with a different VGA monitor in the past.  Something funny with that DELL monitor?

Looking for clues.

Thanks for your time.

Comment 1 Alex Deucher 2011-04-23 08:38:37 UTC

Please attach your xorg log and dmesg output.  There were a number of cards in the r6xx days where the HDMI and VGA port shared the same DDC line so you couldn't use the two ports together.  I suspect this may be what you are seeing.  If this is the case, you'll have to use a DVI to VGA adapter on the DVI port to use the VGA and HDMI monitors together.

Comment 2 Joseph Farmer 2011-04-23 14:04:15 UTC

Created attachment 46003 [details]
dmesg_vgaonly

Comment 3 Joseph Farmer 2011-04-23 14:04:57 UTC

Created attachment 46004 [details]
xorg log vgaonly

Comment 4 Joseph Farmer 2011-04-23 14:05:35 UTC

Created attachment 46005 [details]
dmesg_tvonly

Comment 5 Joseph Farmer 2011-04-23 14:06:05 UTC

Created attachment 46006 [details]
xorg tvonly

Comment 6 Joseph Farmer 2011-04-23 14:06:32 UTC

Created attachment 46007 [details]
dmesg_both

Comment 7 Joseph Farmer 2011-04-23 14:06:54 UTC

Created attachment 46008 [details]
dmesg_both

Comment 8 Joseph Farmer 2011-04-23 14:07:27 UTC

Created attachment 46009 [details]
xorg both

Comment 9 Joseph Farmer 2011-04-23 14:08:03 UTC

Created attachment 46010 [details]
dmesg_hd5450_instead

Comment 10 Joseph Farmer 2011-04-23 14:08:38 UTC

Created attachment 46011 [details]
xorg_hd5450_instead_with_both

Comment 11 Joseph Farmer 2011-04-23 14:10:06 UTC

Ok, swapping with the 5450 clears up that problem.  I'll use that 3450 in the machine from which the 5450 came out of as its monitors have DVI.

So the bug with the 3450 remains but the monitors work around it.  The 5450 can drive the VGA and HDMI at the same time so I'm good.

Thanks for the help.

Comment 12 Alex Deucher 2011-04-24 07:50:56 UTC

Ok, so the oem designed your board to use the same ddc line for both vga and hdmi.  You can't use both VGA and HDMI at the same time with that board.  That's also probably the reason you are getting EDID errors.  If you want to use VGA and HDMI, you will need to use a DVI to VGA adapter on the DVI port for the VGA monitor.

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