Another No HDMI signal detected

KVM
1

Dell R620 server, using a VGA-to-HDMI adapter.

No HDMI signal detected, tried both the front and rear VGA ports.

[root@glkvm:~]# dmesg|grep 6911
[    0.489419] lt6911c 1-002b: version: v1.0.1
[    0.489450] lt6911c 1-002b: driver version: 00.01.03
[    0.489472] lt6911c 1-002b:  Get hdr mode failed! no hdr default
[    0.489496] lt6911c 1-002b: GPIO lookup for consumer reset
[    0.489500] lt6911c 1-002b: using device tree for GPIO lookup
[    0.489526] of_get_named_gpiod_flags: parsed 'reset-gpios' property of node '/i2c@ff510000/lt6911@2b[0]' - status (0)
[    0.489561] lt6911c 1-002b: GPIO lookup for consumer pwdn
[    0.489565] lt6911c 1-002b: using device tree for GPIO lookup
[    0.489583] of_get_named_gpiod_flags: parsed 'pwdn-gpios' property of node '/i2c@ff510000/lt6911@2b[0]' - status (0)
[    0.489603] lt6911c 1-002b: GPIO lookup for consumer resolution
[    0.489607] lt6911c 1-002b: using device tree for GPIO lookup
[    0.489623] of_get_named_gpiod_flags: parsed 'resolution-gpios' property of node '/i2c@ff510000/lt6911@2b[0]' - status (0)
[    0.489642] lt6911c 1-002b: GPIO lookup for consumer hotplug
[    0.489646] lt6911c 1-002b: using device tree for GPIO lookup
[    0.489662] of_get_named_gpiod_flags: parsed 'hotplug-gpios' property of node '/i2c@ff510000/lt6911@2b[0]' - status (0)
[    0.489725] lt6911c 1-002b: could not get sleep pinstate
[    0.489808] lt6911c 1-002b: Linked as a consumer to regulator.3
[    0.489871] lt6911c 1-002b: Linked as a consumer to regulator.1
[    0.489922] lt6911c 1-002b: Linked as a consumer to regulator.2
[    3.290086] lt6911c 1-002b: check chipid ok, id:0x516
[    3.299833] lt6911c 1-002b: Firmware Version: 49.25.3.3.1
[    3.299983] rockchip-mipi-dphy-rx ff4b0000.csi-dphy: match m00_f_lt6911c 1-002b:bus type 4
[    3.300011] 6911 probe exit!
[ 1122.543774] lt6911c 1-002b: 0xD211 is 0
[root@glkvm:~]#

system_logs_20250816_034850.zip (47.1 KB)

Attaching system logs. I tried setting a EDID for a 1024x768 monitor, it had no effect.

Currently using the Asus monitor and Logitech keyboard/mouse profile.

I tested the GL-RM1 and VGA-HDMI adapter on another system, SuperMicro if it matters, and it worked flawlessly, so the adapter works.

Have also confirmed that the keyboard does work. I can press keys (like F1 during POST) and they do effect the remote system.

2

We have analyze the log you provide which shows VGA interface from your controled device has no signal output. Could you please confirm the interface works fine by connecting a monitor to the controled device.

4

Yes, sorry for not mentioning that. A physical monitor connected has no issue.

system_logs_20250817_215512.zip (53.4 KB)

These logs show the 'get 6911c resolution' spam after I 'wake' up the system by typing something (also 1.4.2 R1 now because I tried everything)

5

Could you please try to plug/unplug the HDMI cable to the RM1 for a couple of times, then export the log to us for further analysis.
Thanks for your cooperation.

7

Here is the export.

system_logs_20250817_222422.zip (77.1 KB)

Thank you

8

The log still shows no video signal. According to your description, the RM1 and the same VGA-HDMI cable works fine in another computer? There might be a compatibility issue in the controlled device's motherboard. Please try to update to the latest firmware and see if video display can work. Is there another interface in controled device can use or a different cable.

9

There are two VGA ports on Dell's R620, front and rear, have tried both with the same result, currently connected to the front.

That is correct, that was my first thought, either it wasn't working or wouldn't work with the RM1, so tried it in another system.

Latest firmware for the Dell? Or the RM1?

The Dell's firmware for the BIOS is the latest, the GPU has never had a firmware update.

The RM1, thought I was with 1.4.2 R1 which hasn't hit general release yet?

The IPMI/BMC isn't responding, purchased the RM1 to try and fix it, I can order/ship a different VGA-HDMI adapter to the site if needed, it is 2000km away, using remote hands to do the physical work.

Side question.. With the errors spamming the logs, are there any concerns about excessive small writes to the flash storage? The 'log2ram' package could extend the lifetime of these devices by years if the logs that don't need to be saved are just kept in RAM.

To confirm you want us to get a different VGA-HDMI adapter? This should be interesting to try and find one with a different chipset..

10

Could pls show me a pic about your connection. Did you power the VGA to HDMI adapater?

11

Alright? What specifically would you like to see?

Did you power the VGA to HDMI adapater?

Yes, using the server's USB port near the VGA port, the USB ports have been tested with other devices.

12

OK, I got it. Maybe you need to try another VGA-->HDMI adapter. Some one had test the " BENFEI VGA to HDMI Adapter". you can try it.

13

Alright,

Have the "Elebase VGA to HDMI Adapter" one right now.

It will likely take until the end of the week to get a new one in place. A Benfei I can find. May just 'go big' and order one of the Startech ones.. At least I know know which chipset they use and the resolutions it will work with.

I'll update when I get a different one in place, hopefully by next Monday.

1 Like
14

New VGA-HDMI cable installed today, would have been yesterday but the cable arrived damaged.

Did go with the Startech one, VGA2HDU (VGA2HDMM2M uses the same chipset) because Startech publishes the chipset and list of resolutions it supports.

Best guess.. The previous cable only passes certain resolutions, maybe even only 1920x1080, which the BIOS and OS are not running at on that system.

GL-RM1's web interface shows 1024x768 on the bottom corner which is what I expect to see. Request for the future, perhaps add the refresh frequency too?

It worked until the system was rebooted. :frowning:

Edit: Better but lt6911c 1-002b: lt6911c_rcv_supported_res: unsupported resolution 1024x768@75 comes up as an issue. Will explore different EDID values, see if that will help at all.

The 60Hz maximum refresh rate is a serious limit.. Displays 30 years old would support 75Hz and 85Hz.

1 Like
15

Final solution..

Returning the Comet.. Just wouldn’t work. The note that minmie1 made,

In fact, if you enter an incorrect EDID, it will enable the built-in EDID instead of your incorrect EDID. This may lead you to think you 're using.... In fact, it isn't.

Was the final push for me to contact Amazon’s support and get them to approve a return (couple days past). With no way to see if the Comet was using and sending the EDID I specify and no way to see what the EDID was outputting, it became impossible to troubleshoot. I poked around the OS enough and believe I found the various monitors on from the drop-down menu, they had resolutions enabled that the Comet can’t support.

So the Comet was sent back today.. Looking at a Spider KVM but they have a much higher cost, and more awkward to use ‘virtual media’, however they support higher refresh rates on some resolutions. 1080p (1920x1080) isn’t supported but I really don’t need it, nor audio..

The Comet has potential but it just isn’t ready. I’d classify it as a beta product.