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#1 2019-08-18 10:09:34

Registered: 2016-05-24
Posts: 6

RX 560 and 4k troubles.


I recently exchanged my 1050ti for a RX 560 so I could have hardware H265 10bit decode support for my HTPC.

After installing the card, it wasn't able to detect that my TV can do 4k, even though the previous nvidia card could. I filed a bug about it.

Now the problem is, that if I use 4k 60hz, the sound just drops out. I can toggle my sound on/off by running

`xrandr --output HDMI-A-0 --mode 3840x2160 -r 30` # sound on
`xrandr --output HDMI-A-0 --mode 3840x2160 -r 60` # sound off

I've filed a bug for that too

I've also found that (Weirdly) 4k 60hz with sound works under Wayfire/Wayland, but only Wayfire. Weston 4k 60hz sound doesn't work.

Any ideas? this is my daily driver for the TV in the front room so I kinda need to get it working sometime soon, even if it means selling the card or switching OS.

Thanks smile


#2 2019-08-19 10:21:56

Registered: 2016-05-24
Posts: 6

Re: RX 560 and 4k troubles.

For future googlers:

I got the correct modeline by plugging an nvidia machine into the TV and running xvidtune -show. I stuck that on the RX 560 - still no sound, but in the process I plugging the HDMI enables sound.

So I guess the "workaround" until the above bugs are fixed is:

1) Plug in another machine that does work at 4k 60hz with sound
2) xvidtune -show and steal its modeline
3) add that modeline, you can see examples of how to do that in the bug reports above
4) use xrandr to verify that your TV is running at 4k 60hz
5) replug HDMI, enjoy having sound.

My TV also disconnects itself when turned off, so I can simply put the TV in standby and turn it back on again to get it working. I'm sure there's an IT crowd reference in there somewhere.


#3 2019-08-19 16:11:40

Registered: 2015-03-09
Posts: 832

Re: RX 560 and 4k troubles.

Maybe there's a way to convince the driver that the TV has reconnected through software? The only thing I know is playing around with xrandr, something like this at the bash prompt:

xrandr --disable HDMI-A-0 ; sleep 3 ; xrandr --enable HDMI-A-0

Perhaps doing this kind of thing with xrandr in Xorg will also reach the deeper parts of the driver and reinitialize whatever's broken inside there.

There's also something interesting in /sys/class/drm/. You can find the card's outputs there. This is stuff that's living below Xorg. Maybe some of the files in there are writable and not just readable, and can be used to disable and re-enable an output?

Last edited by Ropid (2019-08-19 16:12:16)


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