Planet USB-C to HDMI Video Cable

[cam1965]

Hi. I figure it out because I  had a similar problem with my dvb stick in linux and solved it ( in cosmo ). Please see :

https://www.oesf.org/forum/index.php?topic=36195.msg295355#msg295355

Maybe this help to create ( compile a new kernel ).
Thanks for help also.

[abliss]

I mentioned on the other thread that root can probe the lt8912b driver at runtime with `echo 14010000.dsi.2 > /sys/bus/mipi-dsi/drivers/panel-vt-lt8912b-vdo/bind` . This doesn't work because the panel index is mismatched from what the dts expects (and I don't understand why it works when the hdmi is plugged from boot--somehow the dts remote-port changes). I tried commenting out that check, but then the device just reboots. It seems, reading drivers/misc/mediatek/devapc, that the kernel worker thread that services the bind command isn't authorized to access the display subsystem, so the cpu generates a violation interrupt. Maybe I can disable this, or figure out some way to get the correct thread to do the probing.

[cam1965]

Thanks for the information.In my test ( hdmi adapter plugged at boot )  the internal display doesn't work together with the hdmi external display. The  internal display of astro is disabled when hdmi is enabled. This is strange.

[cam1965]

Answer from Planet : (In bold  the text about the hdmi problem )

 Paul E. Pinnock (Planet Computers)

Welcome back.
At this moment, it is prohibited to ship battery only, should you wish for us to replace your Gem or Cosmo battery, the battery service is available. In regard to the connection issue, we will investigate and revert.
Thank you for your patience.

[Ian Glendinning]

Hi, Thanks for the tip that a reboot is necessary and for the video. I have just noticed that in the Astro Slide quick start guide it says that the left hand side USB-C port supports HDMI video out via the Planet USB-C to HDMI video cable and it says "Astro Reboot required"!

I have just tried this, and unfortunately it doesn't work for me though :-( The Astro reboots as normal, and nothing appears on my TV screen... It works with my Cosmo, so either my Astro is somehow broken, or my TV isn't compatible with the Astro's HDMI output for some reason. I'll try to find another screen to test it with.

[Zarhan]

I have just tried this, and unfortunately it doesn't work for me though :-( The Astro reboots as normal, and nothing appears on my TV screen... It works with my Cosmo, so either my Astro is somehow broken, or my TV isn't compatible with the Astro's HDMI output for some reason. I'll try to find another screen to test it with.

For me the reboot trick works, but only with my computer monitor. The Astro's output resolution is apparently something that throws a TV (that just supports your regular TV resolutions) off.

Try with a computer monitor that can sync with any resolution.

[LinuxGuy]

Hi
Same issue here. Tried with modern computer monitor: no signal
<sigh>

[Zarhan]

Hi
Same issue here. Tried with modern computer monitor: no signal
<sigh>

Did you remember to do power-cycle while the HDMI dongle was attached to the *left* side USB port?

(On Cosmo, the USB port to use for HDMI is on the right side. This threw me off too).

[LinuxGuy]

Yes I rebooted pluged in in the left usb c.

[ZimbiX]

Anyone know what resolution it's trying to output? I haven't given it a go with mine yet - I have yet to dig out my Planet HDMI adapter

[Zarhan]

Anyone know what resolution it's trying to output? I haven't given it a go with mine yet - I have yet to dig out my Planet HDMI adapter

I did a test just now. My adapter is one I got for Cosmo.

Procedure: Attach HDMI cable to adapter, attach adapter to left side USB port of Astro, reboot (power-cycle not required, reboot is enough).
NOTE: the HDMI cable needs to be connected to the adapter during reboot. Otherwise it doesn't work (at least for me).

The resolution is 1280x720, 60 Hz. (45.1 kHz horizontal sync). So actually, this *should* work even with TVs. Cosmo had a non-standard resolution.

Note that the touchscreen becomes disabled, so you have to enter e.g. pin codes from the keyboard.

When you disconnect the adapter, the device reboots again and you get your touchscreen back.

[ZimbiX]

Thanks for checking that, Zarhan.

720p is lower resolution than I'd hoped (I'd expected 1080p), but at least it's a standard resolution and aspect ratio, unlike the previous devices. Strange that it's not working on some monitors - perhaps the device is not detecting the presence of the monitor somehow...

I wonder if there's a way to get it to output 1080p.

It's probably worth putting together a wiki page on all this.

[Zarhan]

720p is lower resolution than I'd hoped (I'd expected 1080p), but at least it's a standard resolution and aspect ratio, unlike the previous devices. Strange that it's not working on some monitors - perhaps the device is not detecting the presence of the monitor somehow...

Low resolution is annoying, but the problem that kills the usability for me is that unlike Cosmo, it's not a mirrored screen where you see the image on both displays at once, but the image *only* appears on the monitor. So the touchscreen gets disabled.

I guess you could hook up a mouse (bluetooth or via the USB hub), but still non-optimal solution if I'd just quickly like to show some pictures or something on a big screen.

Oh, and of course the whole "reboot whenever you attach/detach the adapter" as well.

[LinuxGuy]

Yes I rebooted pluged in in the left usb c.

Got it working!
used an not so cheap HP e24 g4 monitor! Settings: DP-hotplug active and autoswitch on

Hope that helps someone!

[ZimbiX]

@LinuxGuy Is that a different monitor to what you were trying to use before?