Initial commit: rtw89-steam-frame DKMS wrapper

DKMS package that fetches the in-tree rtw89 source for the target kernel,
applies the steam-frame patches, and builds/installs the patched RTL8852CU
modules for the Valve Steam Frame wireless adapter.

- dkms.conf: module list + install locations
- build.sh: fetch (gregkh/linux) + patch + build + verify
- register.sh: clone upstream patches, stage into /usr/src, dkms add/build/install

GPL-2.0-only.

README.md

@@ -0,0 +1,58 @@
+<!-- SPDX-License-Identifier: GPL-2.0-only -->
+
+# rtw89-steam-frame dkms
+
+DKMS wrapper for the patched Realtek rtw89 driver used by the **Valve Steam Frame**
+wireless adapter (`28de:2432`, RTL8852CU).
+
+It builds the *in-tree* rtw89 source for whatever kernel you run (fetched from
+`gregkh/linux`), applies the **steam-frame patches** (pulled at register time via git
+from [Davenport-Physics/rtw89-steam-frame](https://github.com/Davenport-Physics/rtw89-steam-frame)),
+and auto-rebuilds on every kernel upgrade through the Arch DKMS pacman hooks.
+
+## Why
+
+The Frame advertises a 6 GHz **VLP** power class and the stock driver honors it,
+capping the dongle at 7/4 dBm (1TX/2TX) — roughly 10 dB below what the Windows driver
+uses. That deficit caused MAC-layer retry storms and bursty micro-stutters in VR
+streaming (see [SteamVR-for-Linux#965](https://github.com/ValveSoftware/SteamVR-for-Linux/issues/965)).
+
+`reg6_pwr_override=1` switches the adapter to the **LPI** table (12/11 dBm at 160 MHz),
+which on this system removed the missed-frame stalls even at ~1.8x the previous load.
+`disable_2ghz=Y` additionally disables the useless 2.4 GHz band (and the scan-offload
+USB resets associated with it).
+
+## Install / re-register
+
+    ./register.sh         # As root
+
+This clones upstream, stages `/usr/src/rtw89-steam-frame-0.1`, and runs
+`dkms add/build/install` for the current kernel. After that, the Arch pacman hooks
+(`/usr/share/libalpm/hooks/70-dkms-*`) rebuild it automatically on every kernel update.
+
+Optional env overrides: `RTW89_UPSTREAM`, `RTW89_UPSTREAM_REF`, `RTW89_KVER`.
+
+## Preconditions
+
+- `linux-headers` installed and kept in sync with `linux`.
+- Network access at (re)build time — the kernel's rtw89 source and the patches are
+  both fetched over HTTPS.
+
+## Files
+
+| file          | purpose |
+|---------------|---------|
+| `dkms.conf`   | DKMS metadata (module list, install location) |
+| `build.sh`    | DKMS build step: fetch rtw89 for `$kernelver`, patch, build, verify |
+| `register.sh` | pull upstream patches via git, stage, `dkms add/build/install` |
+
+## Module parameters
+
+Add this to `modprobe.d`, e.g. `/etc/modprobe.d/rtw89-steam-frame.conf`:
+
+    `options rtw89_core reg6_pwr_override=1 disable_2ghz=Y`
+
+You might also want to disable advanced power management if not done so already
+(also supported by in-kernel driver):
+
+    `options rtw89_core disable_ps_mode=Y`