This is also happening to me. I have an HP EliteBook 6930p (running bullseye) that, once it goes to sleep, looks and sounds like it's waking up, but the screen remains black and I'm unable to SSH to it any more.
[excerpt from 'inxi -Fxxx'] System: Host: joethelion Kernel: 5.6.0-1-amd64 x86_64 bits: 64 compiler: gcc v: 9.3.0 Desktop: Gnome 3.36.2 wm: gnome-shell dm: GDM3 3.34.1 Distro: Debian GNU/Linux bullseye/sid Machine: Type: Laptop System: Hewlett-Packard product: HP EliteBook 6930p v: F.0F serial: <superuser/root required> Chassis: type: 10 serial: <superuser/root required> Mobo: Hewlett-Packard model: 30DB v: KBC Version 87.24 serial: <superuser/root required> BIOS: Hewlett-Packard v: 68PCU Ver. F.0F date: 03/05/2009 Battery: ID-1: BAT0 charge: 49.4 Wh condition: 49.8/55.1 Wh (90%) volts: 12.5/10.8 model: Hewlett-Packard Primary type: Li-ion serial: 07253 2009/03/26 status: Unknown CPU: Topology: Dual Core model: Intel Core2 Duo P8400 bits: 64 type: MCP arch: Penryn rev: A L2 cache: 3072 KiB flags: lm nx pae sse sse2 sse3 sse4_1 ssse3 bogomips: 9044 Speed: 798 MHz min/max: 800/2267 MHz boost: enabled Core speeds (MHz): 1: 798 2: 798 Graphics: Device-1: Intel Mobile 4 Series Integrated Graphics vendor: Hewlett-Packard driver: i915 v: kernel bus ID: 00:02.0 chip ID: 8086:2a42 Display: wayland server: X.Org 1.20.8 compositor: gnome-shell driver: i915 note: display driver n/a resolution: 1440x900~60Hz s-dpi: 96 OpenGL: renderer: Mesa DRI Mobile Intel GM45 Express v: 2.1 Mesa 19.3.3 direct render: Yes
