Re: [RFC PATCH] drm/amd/display: extend HPD debounce filter to DisplayPort SST

[Michel Dänzer]

[ Adding Xaver for awareness ]

On 6/25/26 21:45, Nick Haghiri wrote:
> On 6/25/26 3:15 PM, Ivan Lipski wrote:
>> I don't think I've encountered a situation when a monitor with DP can
>> wake a system up from DPMS, so that's interesting. What distro and
>> desktop environment are you using? I'd like to reproduce this issue
>> and help with it.
> 
> openSUSE Tumbleweed, KDE Plasma 6.7 on Wayland (KWin). GPU is an RX 9070
> XT (RDNA4), monitor is an MSI MPG 274U over DisplayPort SST.
> 
> What happens: when the output goes DPMS-off and the monitor drops into
> deep sleep, it briefly de-asserts and re-asserts HPD. amdgpu forwards
> that as a hotplug, KWin re-probes and re-enables the output, and the
> panel comes right back on, so it never actually stays asleep while
> connected.

FWIW, that the panel comes on and stays on might be a KWin bug. Mutter had a bug like that, which I fixed in https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/4209/diffs?commit_id=ec73076e07640fc0752d9ecc66c5934726db2d7e.


P.S. For other reasons, mutter also has debouncing similar to this. If the kernel debounces as well, it'll take longer until mutter actually removes an unplugged display from its display configuration, hopefully not too bad though.

-- 
Earthling Michel Dänzer       \        GNOME / Xwayland / Mesa developer
https://redhat.com             \               Libre software enthusiast