Hi,i need get VGA(1080P), want use a converter which can convert eDP(V1.3) to VGA.but the converter only support 2 Main Link Lanes eDP input signal,though i know 2 main lanes is enough for the VGA’s bandwidth .Can i choose lane 0 and lane 1 for the 2-lane usage for the converter’s input signal,is the way be OK and how to config for 2-lane ?i also find eDP Connection Example in a jetson OEM. thanks for you reply.
VGA lacks the DDC wire (which sends the monitor’s specs, the EDID data). You need a format which has the DDC wire (e.g., native HDMI or actual DisplayPort with a DisplayPort to HDMI adapter). If not, then you need an active adapter which send custom programmed EDID data set up for that monitor.
I think vga has the ddc wiring, but the protocol used is not the same now.
Anyway, pedant aside, linuxdev is correct and the Nano is known to not work with a VGA monitor, even with adapters and I think even if you manually specify a mode. If you do manage to get it to work however, please share your configuration as there are others on the forum who desire the same setup.
Hello,since get VGA unworkable,in other words,i need get analog output(1080P will be the best),is there any effective methods,can i get you advice?thanks.
Is your target display a TV with component inputs? You could try something like this or a fancier upscaler box (eg. DVDO).
I think the best you will get over component is 1080i and there is no guarantee it’ll work with the Nano either. You can try it and see. I can find no threads on whether it works or not.
Trivia: Newer monitors which have both VGA and HDMI can pass through DDC. Older monitors without a native DDC supporting output can have the wire, but not implement any response. I have not actually ever seen a VGA monitor (without other connectors) which has a valid EDID…it would certainly be a surprise for me if one worked.
Hello,that right,i choose newer monitors which have both VGA and HDMI.i plan use 2-lane DisplayPort to VGA adapter IC(e.g. PTN3392(NXP) or CH7517(Chrontel)),but i get the advice there is nobody do it in this way,and i have no enough time to try it myself.so i have a question ,is the output of the DP/eDP are not follow its spcification?can i have other ways?thanks.
Not sure if this will help, but some trivia around the topic follows…
Originally the DDC wire had a requirement for the layout of data from an i2c query. This was later updated, and eventually “extended” versions were created. Mostly these were intended to be able to append more data rather than replace the original format, but this is when it became known as “EDID” (https://en.wikipedia.org/wiki/Extended_Display_Identification_Data).
There may be older variants which simply don’t work. Add to this that the embedded system drivers for the GPU do not accept certain extensions, nor do they accept interlaced modes. Only a subset of the EDID will work on the embedded systems even if they work on a full desktop PC driver.
To see if your EDID is being sent, find the hex data while the monitor is connected with your adapter:
sudo -s cat `find /sys -name 'edid'` exit
If the EDID is empty, then there is no possibility of this working in any way other than luck or artificially providing an EDID (such as through a programmed active adapter). If there is EDID data, then copy and paste the hex data here and see if the checksum is valid:
If the checksum is valid, and there is still failure, then you will want the NVIDIA driver to verbosely log what it thinks of each mode. Usually this can be accomplished by editing the “Device” section of “/etc/X11/xorg.conf”:
Section "Device" ... Option "ModeDebug" ... EndSection
The log should be in “/var/log/Xorg.0.log”. You would then search for the accepted “mode pool” to see if anything is allowed from the list of EDID modes. You will likely find some extension modes and any interlaced modes to be summarily rejected. Modes manually added to “/etc/X11/xorg.conf” will also be rejected as only EDID modes are allowed.