arm2
Posts: 253
Joined: Thu Dec 15, 2011 3:46 pm

EDID files for DVI monitors/adaptors that don't display

Tue Jun 05, 2012 7:49 pm

All using Debian 19.4.12 official download:
BenQ G2420HDB HDMI input works with no config.txt
using its DVI input and
with hdmi_force_hotplug=1
BenQ G2420HD (DVI & VGA only) also gives no display and same EDID file:
http://www.cjemicros.f2s.com/public/edid.dat

Powered HDMI to VGA adaptor no display with no config.txt
with hdmi_force_hotplug=1 I get a display if hdmi_mode= set to:
VGA
640x480 & 800x600
1024x768 & Higher resolutions gave no display
http://www.cjemicros.f2s.com/public/edid2.dat

UnPowered HDMI to VGA adaptor no display with no config.txt
with hdmi_force_hotplug=1 I get a display if hdmi_mode= set to:
VGA
640x480
800x600
&
1024x768 but all modes 'glitching' every few seconds and display funny i.e. on some lines the text was displayed sort of italic!
Higher resolutions gave no dsiplay
http://www.cjemicros.f2s.com/public/edid3.dat

with MODE 35: 1280x1024 composite displayed!

Both HDMI to VGA adaptors are quoted as up to 1920x1080

I tried
config_hdmi_boost=5

n.b. I know config.txt was being parsed as with:
hdmi_group=2
hdmi_mode=19
disable_overscan=1

overscan was disabled

Anything else to try?

dom
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5572
Joined: Wed Aug 17, 2011 7:41 pm
Location: Cambridge

Re: EDID files for DVI monitors/adaptors that don't display

Tue Jun 05, 2012 10:04 pm

Can you update firmware (eg with Hexxeh's rpi-update tool) and confirm if they are still failing?

arm2
Posts: 253
Joined: Thu Dec 15, 2011 3:46 pm

Re: EDID files for DVI monitors/adaptors that don't display

Fri Jun 08, 2012 1:55 pm

After running rpi-update with dependancy updates and ignoring one error, significant improvement.

All tests using Benq G2420HD Monitor (HDMI, DVI & VGA inputs)
& hdmi_force_hotplug=1

The DVI input now works (As now does the DVI input on the version of the G2410 with no HDMI)
tested @ 1080p
& 1280 x 1024

White unpowered HDMI - VGA adaptor (1080p capable)
o.k. in VGA
800x600
& 1024 768
but glitching & shearing in 1280x1024 high resolutions not displayed
group 1 mode 19 i.e. 720p gave 640x480!
group 1 mode 16 i.e. 1080p gave no display

Powered HDMI-VGA now:

Group 1 Mode 16 1920x1080 works
Group 1 Mode 19 720p works
Strangely
group 2 mode 35 i.e. 1280 x 1024 60hz gave 640x480!

n.b. I found one website selling the White unpowered HDMI to VGA adaptor quote Power consumption as 190mA

dom
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5572
Joined: Wed Aug 17, 2011 7:41 pm
Location: Cambridge

Re: EDID files for DVI monitors/adaptors that don't display

Fri Jun 08, 2012 3:52 pm

arm2 wrote: White unpowered HDMI - VGA adaptor (1080p capable)
group 1 mode 19 i.e. 720p gave 640x480!
EDID says that mode is not supported.
arm2 wrote: Powered HDMI-VGA now:
group 2 mode 35 i.e. 1280 x 1024 60hz gave 640x480!
EDID says that mode is not supported.

Currently the behaviour when the mode is not supported is to output VGA (which is manditory) in the requetsed group.
arm2 wrote:n.b. I found one website selling the White unpowered HDMI to VGA adaptor quote Power consumption as 190mA
Yes, I think that is the problem with unpowered adaptor. I believe HDMI only gaurantees 50mA, so not surprised it is flaky...

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