From 00475b637b3a908ad4fdf83dad09327b66b1d2ca Mon Sep 17 00:00:00 2001
From: Alexander Heldt <me@alexanderheldt.se>
Date: Fri, 2 Oct 2026 09:45:20 +0200
Subject: [PATCH] pinwheel: Give the webcam `v4l2loopback` device more buffers

---
 hosts/pinwheel/modules/webcam/default.nix | 37 +++++++++++++++--------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/hosts/pinwheel/modules/webcam/default.nix b/hosts/pinwheel/modules/webcam/default.nix
index 5a658b5..95df1e3 100644
--- a/hosts/pinwheel/modules/webcam/default.nix
+++ b/hosts/pinwheel/modules/webcam/default.nix
@@ -1,4 +1,4 @@
-{ ... }:
+{ config, lib, ... }:
 {
   nixpkgs.overlays = [
     (final: prev: {
@@ -11,18 +11,19 @@
       });
 
       gst_all_1 = prev.gst_all_1 // {
-        icamerasrc-ipu6epmtl = (prev.gst_all_1.icamerasrc-ipu6epmtl.override {
-          ipu6-camera-hal = final.ipu6epmtl-camera-hal;
-        }).overrideAttrs
-          (old: {
-            version = "20250923_ov02e";
-            src = final.fetchFromGitHub {
-              owner = "intel";
-              repo = "icamerasrc";
-              tag = "20250923_ov02e";
-              hash = "sha256-mKRK0Z3dnyvzvoL6BotpVFRtkb53GQw9wUOrHIUoEsA=";
-            };
-          });
+        icamerasrc-ipu6epmtl =
+          (prev.gst_all_1.icamerasrc-ipu6epmtl.override {
+            ipu6-camera-hal = final.ipu6epmtl-camera-hal;
+          }).overrideAttrs
+            (old: {
+              version = "20250923_ov02e";
+              src = final.fetchFromGitHub {
+                owner = "intel";
+                repo = "icamerasrc";
+                tag = "20250923_ov02e";
+                hash = "sha256-mKRK0Z3dnyvzvoL6BotpVFRtkb53GQw9wUOrHIUoEsA=";
+              };
+            });
       };
     })
   ];
@@ -31,4 +32,14 @@
     enable = true;
     platform = "ipu6epmtl";
   };
+
+  systemd.services.v4l2-relayd-ipu6 = {
+    preStart = lib.mkOverride 40 ''
+      mkdir -p "$(dirname "$V4L2_DEVICE_FILE")"
+      ${config.boot.kernelPackages.v4l2loopback.bin}/bin/v4l2loopback-ctl \
+        add --name "Intel MIPI Camera" --exclusive-caps=1 --buffers 8 \
+        ${toString config.hardware.ipu6.videoDeviceNumber} || [ $? -eq 17 ]
+      echo /dev/video${toString config.hardware.ipu6.videoDeviceNumber} > "$V4L2_DEVICE_FILE"
+    '';
+  };
 }