Lucie / minute1d ago

hell yeah, got displayport alt mode over usb-c working on rk3588 pocket reform with mainboard 2.0!

in the end it was a DP lane polarity issue: USB3 allows lane polarity swap for better PCB routing, but DP doesn't. tricky when you need to reuse the same lanes for both.

Show threadLucie / minute
but wait... does that mean MNT Pocket Reform can have 3 displays now (1 DP, 1 HDMI, 1 internal)? yes, yes it can!
Apr 8 at 10:41pmTusky
Show threadAlison Wilder1d ago
@mntmn holy shit, you just keep making this thing COOLER AND COOLER
Show threadjosch1d ago
@alisynthesis @mntmn I feel we need to somehow stuff the pocket reform mainboard into a classic reform case to have the classic reform have feature parity compared to the pocket reform (not just because of display port alt mode over usb-c but also because the pocket has wifi, bluetooth and umts with rk3588...)
Show thread[tj] - knows what your packets are thinking1d ago
@josch @alisynthesis @mntmn imagine the batteries you could get in there with a tiny mainboard!
Show threadjosch1d ago
@tj @alisynthesis @mntmn More seriously I am hoping that we can re-use the Reform Next mainboard in the classic Reform. It already has support for eight LiFePo4 batteries, for the panel and since the left/right port board are separate you could create a port board with full size ethernet for example. :)
Show threadgahlord1d ago
@mntmn Will it drive an Apple XDR? Asking for a friend.
Show threadLucie / minute1d ago
@gahlord unfortunately i don't have one to test with :D
Show threadgahlord1d ago
@mntmn haha if only I had a little MNT I could test it for you. :) Maybe eventually
Show threadLuke Wren1d ago
@mntmn Finally a thumb grabby thing that doesn't look like a MacBook
Show threadLuke Wren1d ago
@mntmn The number of manufacturers doing exactly this feature is too damn high
Show threadLucie / minute1d ago
@wren6991 ahhh now i get it :D yes, deliberate
Show threadTravis F W1d ago
@mntmn @wren6991 but what do you CALL it??
Show threadsiviq1d ago
@mntmn Bare aluminum case looks interesting to me. Any plans to release it as purchase along the mainboard 2.0?
Show threadAlex Seibz1d ago
@mntmn
I love you and I still want this. Maybe by my birthday at the end of the year! Will you be shipping towards the end of December or no?
Show threadIgnas Kiela1d ago
@mntmn no DP MST support?
Show threadLucie / minute1d ago
@ignaloidas no, but i also don't have a display that can do that
Show threadWolf480pl1d ago
@mntmn
USB-C hubs with multiple display outputs usually use MST, maybe one of those would be easier to get than an MST-supporting display?
@ignaloidas
Show threadIgnas Kiela1d ago
@wolf480pl @mntmn yeah, my thoughts on usage are the same

Though it seems like rk3588 can't support MST, while the (lower-end) RK3576 can https://lwn.net/Articles/1031560/
Add support for RK3588 DisplayPort Controller

LWN.net
Show threadLucie / minute1d ago
@ignaloidas @wolf480pl yeah i also remember this as a newer feature. also not sure how useful it would be for 2 lanes
Show threadIgnas Kiela1d ago
@mntmn @wolf480pl how high can they clock? You could drive two 1080p monitors with that if it can go to HBR2
Show threadWolf480pl1d ago

@mntmn
If I'm reading the table here
https://en.wikipedia.org/wiki/DisplayPort#Refresh_frequency_limits_for_common_resolutions
correctly ( it's for 4 lanes so divide fps by 2, then by 60 to see how many monitors fit)

with 2 lanes and HBR3 one should be able to get 2x 1440p60Hz, right?

@ignaloidas

DisplayPort - Wikipedia

Show threadIgnas Kiela1d ago
@wolf480pl @mntmn yeah, and it seems like rk3588 does support HBR3 so it should be able to do it, and that's certainly useful

Also supports DSC if we want to go that route as well