Are you using the beta build (916)? If not, try switching to the beta build and see if that helps.

Originally posted by Packetdancer:

Are you using the beta build (916)? If not, try switching to the beta build and see if that helps.

Yeah tried beta and stable

if anyone has same controllers im sure can reproduce. just moving mouse on desktop

Hm. Okay. Can you get the logs off the Link? Using the "Save Debug Logs" should dump them to the PC (as steamlink_debug.txt in the Steam logs directory) next time you stream, though if you've enabled ssh on the box you could just grab the logs from /mnt/scratch/log -- I'm particularly curious about /mnt/scratch/log/S13bluetooth.sh

FWIW, I'm pretty sure I know what's going on, but the logs would help me confirm it, hence why I'm hoping you can get them. If you can't get them, I'll probably just try to test the theory this coming week, but as I also think the issue is firmware-dependent... that might be tricky.

As for what I *suspect* is happening, just in case you're curious...

So, Bluetooth has what's called a "connection interval." It's not a single 'stream' of information, per se, but rather like the computer and device passing notes to each other. The connection interval is how long you wait between passing notes; a longer connection interval makes things slower (but way more efficient on battery), a shorter one reduces latency (but since you're constantly 'passing notes' it basically exhausts the battery more quickly).

Older versions of Linux had a particularly long default minimum connection interval, and it seems the 8BitDo Ultimate 2 (at least on the firmware you have) is not bothering to negotiate a new one. However, due to how Bluetooth works, the connection range kind of gets decided by whatever the fastest and slowest devices are. The DualSense negotiates a truly *breathtakingly* short connection interval -- meaning extremely low-latency, but not great on battery life -- so you connecting the DualSense causing the latency to go away is exactly what I'd expect if the 8BitDo was saying "I'm good with whatever you want, Steam Link."

As a side note, I *think* if you update the 8BitDo Ultimate 2's firmware (using their Windows or macOS support app), the problem will *probably* go away. *However*, if you can avoid doing that for a couple of days, I'd almost prefer you didn't; if I can't find an affected firmware image for the Ultimate 2 somewhere in the Dimension of Strange Controllers (e.g. the shelf with all of the Steam Link gear), I'd really love to be able to change the default connection interval on the Link's Linux image and have you test.

(Unfortunately, for the Link's version of Linux that requires literally recompiling the kernel, so requires rolling an entire build.)

Originally posted by Packetdancer:

FWIW, I'm pretty sure I know what's going on, but the logs would help me confirm it, hence why I'm hoping you can get them. If you can't get them, I'll probably just try to test the theory this coming week, but as I also think the issue is firmware-dependent... that might be tricky.

As for what I *suspect* is happening, just in case you're curious...

So, Bluetooth has what's called a "connection interval." It's not a single 'stream' of information, per se, but rather like the computer and device passing notes to each other. The connection interval is how long you wait between passing notes; a longer connection interval makes things slower (but way more efficient on battery), a shorter one reduces latency (but since you're constantly 'passing notes' it basically exhausts the battery more quickly).

Older versions of Linux had a particularly long default minimum connection interval, and it seems the 8BitDo Ultimate 2 (at least on the firmware you have) is not bothering to negotiate a new one. However, due to how Bluetooth works, the connection range kind of gets decided by whatever the fastest and slowest devices are. The DualSense negotiates a truly *breathtakingly* short connection interval -- meaning extremely low-latency, but not great on battery life -- so you connecting the DualSense causing the latency to go away is exactly what I'd expect if the 8BitDo was saying "

As a side note, I *think* if you update the 8BitDo Ultimate 2's firmware (using their Windows or macOS support app), the problem will *probably* go away. *However*, if you can avoid doing that for a couple of days, I'd almost prefer you didn't; if I can't find an affected firmware image for the Ultimate 2 somewhere in the Dimension of Strange Controllers (e.g. the shelf with all of the Steam Link gear), I'd really love to be able to change the default connection interval on the Link's Linux image and have you test.

(Unfortunately, for the Link's version of Linux that requires literally recompiling the kernel, so requires rolling an entire build.)

This is really great info thank you. I will get logs when im able to get a chance. Amazing write up thank you

Okay, for what it's worth, with two 8BitDo Ultimate 2 controllers -- one of them running firmware v1.02 and one running firmware v1.09 -- I can reproduce the latency issue with firmware v1.02, but *not* with v1.09.

I'd be curious what firmware version your 8BitDo Ultimate 2 has (the 8BitDo Ultimate Windows app that lets you do firmware updates will tell you). I will not at *all* be shocked if you're before v1.06; I don't have v1.06 here specifically, but I know that's where they added support for using the controller on Switch 2 and made a bunch of changes to the Bluetooth connection glue as a result. I haven't hauled these down to somewhere I can use a Bluetooth sniffer without losing my sanity (we have KIND OF A LOT of Bluetooth wireless devices here), but my gut feeling is that those Bluetooth changes in 8BitDo firmware v1.06 probably included "explicitly asking for decent connection parameters."

In part because I know the Switch 2 wants controllers to ask for connection parameters.

At any rate: if you are able to update your firmware using the Windows app, the problem should in theory go away. (So, no, you don't need to hold off on firmware update any longer -- since we have a controller with firmware v1.02 I have an older firmware to test with.)

If you are not able to update the 8BitDo's firmware, then *Steam Link* firmware build 917 will include some changes to the default connection parameters in the Linux kernel that should also alleviate the problem.