PlanB
Posts: 102
Joined: Tue Oct 28, 2014 6:44 am

edid problem

Wed Mar 13, 2019 2:17 am

I've got 2 monitors I use interchangeable with a pi. The HP monitor self identifies

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root@raspberrypi:/home/pi# tvservice -n
device_name=HWP-HP_L1755
as & it is happy with the preferred hdmi settings

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root@raspberrypi:/home/pi# tvservice -s
state 0x120006 [DVI DMT (35) RGB full 5:4], 1280x1024 @ 60.00Hz, progressive
the other monitor doesn't identify

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root@raspberrypi:/home/pi# tvservice -n
[E] No device present
& so I can't use something like

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[EDID=No device present]
hdmi_group=2
hdmi_mode=87
hdmi_cvt=1024 600 60 6 0 0 0    #1024x600 7"
in /boot/config.txt to identify it & apply it's hdmi settings

Can anyone see a way to load the an alternate set of hdmi settings when the pi boots with the other monitor? I've tried things like

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[EDID!=HWP-HP_L1755]
hdmi_group=2
hdmi_mode=87
hdmi_cvt=1024 600 60 6 0 0 0    #1024x600 7"
but so far no joy

User avatar
rpdom
Posts: 15921
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: edid problem

Wed Mar 13, 2019 7:11 am

I've just tried a few things using an edid dump from one of my monitors and the edid name of another monitor. If you can manage to get the edid info for the unnamed monitor this may work for you.

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# Set default to use edid from file
hdmi_edid_file=1

# but override that setting if this monitor is detected
[EDID=HWP-HP_L1755]
hdmi_edid_file=0

# Carry on with everything else
[all]
It's unusual for an HDMI monitor not to identify itself.

PlanB
Posts: 102
Joined: Tue Oct 28, 2014 6:44 am

Re: edid problem

Wed Mar 13, 2019 11:50 am

That's a nice idea except the edid info for the non identifying monitor is wrong, edid wants to use mode4 whereas the non identifying monitor needs mode87. I know what settings the non identifying monitor needs I just can't figure out a way to apply them when it doesn't identify.

User avatar
rpdom
Posts: 15921
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: edid problem

Wed Mar 13, 2019 1:07 pm

Another possibility would be to create a custom edid file with the settings you want in it. That might not work with your 1024x600 layout. Don't ask me how to do it, but I believe it is possible ;-)

What would be nice is if you could have something in config.txt like this

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[EDID!=HWP-HP_L1755]
hdmi_group=2
hdmi_mode=87
hdmi_cvt=1024 600 60 6 0 0 0    #1024x600 7"
To mean "If the EDID name is NOT HWP-HP_L1755, use this block".

PlanB
Posts: 102
Joined: Tue Oct 28, 2014 6:44 am

Re: edid problem

Wed Mar 13, 2019 10:57 pm

Yeah, my idea of a neat solution too! Alas EDID!= don't work for whatever reason.

User avatar
lh61
Posts: 6
Joined: Wed Mar 06, 2019 5:10 am
Location: Rennes, France

Re: edid problem

Wed Mar 13, 2019 11:46 pm

@PlanB
It's a duplicate of my recent issue (I even provided both EDID ROM) and YOU got answers but not me.
I'm terribly jealous. Obviously you found a better title and your content is easier too understand :mrgreen:
It seems you too have a WaveShare LCD, isn't it?

PlanB
Posts: 102
Joined: Tue Oct 28, 2014 6:44 am

Re: edid problem

Thu Mar 14, 2019 12:51 am

I think it's a waveshare knockoff maybe? Either way it's causing more grief than it's worth! So challenging for a UserLand plod like me to tangle with something like EDID!

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