From dc64193a62f7387363ea01dccdac16bb1fd6d551 Mon Sep 17 00:00:00 2001
From: Colin <colin@uninsane.org>
Date: Sat, 26 Aug 2023 19:49:51 +0000
Subject: [PATCH] moby: generalize sun4i init failure to displayManager *and*
 greetd

---
 hosts/by-name/moby/default.nix | 40 -------------------------------
 hosts/by-name/moby/kernel.nix  | 43 ++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 40 deletions(-)

diff --git a/hosts/by-name/moby/default.nix b/hosts/by-name/moby/default.nix
index 65244730..46c86ebc 100644
--- a/hosts/by-name/moby/default.nix
+++ b/hosts/by-name/moby/default.nix
@@ -132,44 +132,4 @@
   '';
 
   hardware.opengl.driSupport = true;
-
-  services.xserver.displayManager.job.preStart = let
-    dmesg = "${pkgs.util-linux}/bin/dmesg";
-    grep = "${pkgs.gnugrep}/bin/grep";
-    modprobe = "${pkgs.kmod}/bin/modprobe";
-  in ''
-    # common boot failure:
-    # blank screen (no backlight even), with the following log:
-    # ```syslog
-    # sun8i-dw-hdmi 1ee0000.hdmi: Couldn't get the HDMI PHY
-    # ...
-    # sun4i-drm display-engine: Couldn't bind all pipelines components
-    # ...
-    # sun8i-dw-hdmi: probe of 1ee0000.hdmi failed with error -17
-    # ```
-    #
-    # in particular, that `probe ... failed` occurs *only* on failed boots
-    # (the other messages might sometimes occur even on successful runs?)
-    #
-    # reloading the sun8i hdmi driver usually gets the screen on, showing boot text.
-    # then restarting display-manager.service gets us to the login.
-    #
-    # NB: the above log is default level. though less specific, there's a `err` level message that also signals this:
-    # sun4i-drm display-engine: failed to bind 1ee0000.hdmi (ops sun8i_dw_hdmi_ops [sun8i_drm_hdmi]): -17
-    # NB: this is the most common, but not the only, failure mode for `display-manager`.
-    # another error seems characterized by these dmesg logs, in which reprobing sun8i_drm_hdmi does not fix:
-    # ```syslog
-    # sun6i-mipi-dsi 1ca0000.dsi: Couldn't get the MIPI D-PHY
-    # sun4i-drm display-engine: Couldn't bind all pipelines components
-    # sun6i-mipi-dsi 1ca0000.dsi: Couldn't register our component
-    # ```
-
-    if (${dmesg} --kernel --level err --color=never --notime | ${grep} -q 'sun4i-drm display-engine: failed to bind 1ee0000.hdmi')
-    then
-      echo "reprobing sun8i_drm_hdmi"
-      # if a command here fails it errors the whole service, so prefer to log instead
-      ${modprobe} -r sun8i_drm_hdmi || echo "failed to unload sun8i_drm_hdmi"
-      ${modprobe} sun8i_drm_hdmi || echo "failed to load sub8i_drm_hdmi"
-    fi
-  '';
 }
diff --git a/hosts/by-name/moby/kernel.nix b/hosts/by-name/moby/kernel.nix
index ec540cb5..dcb03979 100644
--- a/hosts/by-name/moby/kernel.nix
+++ b/hosts/by-name/moby/kernel.nix
@@ -1,4 +1,44 @@
 { pkgs, ... }:
+let
+  dmesg = "${pkgs.util-linux}/bin/dmesg";
+  grep = "${pkgs.gnugrep}/bin/grep";
+  modprobe = "${pkgs.kmod}/bin/modprobe";
+  ensureHWReady = ''
+    # common boot failure:
+    # blank screen (no backlight even), with the following log:
+    # ```syslog
+    # sun8i-dw-hdmi 1ee0000.hdmi: Couldn't get the HDMI PHY
+    # ...
+    # sun4i-drm display-engine: Couldn't bind all pipelines components
+    # ...
+    # sun8i-dw-hdmi: probe of 1ee0000.hdmi failed with error -17
+    # ```
+    #
+    # in particular, that `probe ... failed` occurs *only* on failed boots
+    # (the other messages might sometimes occur even on successful runs?)
+    #
+    # reloading the sun8i hdmi driver usually gets the screen on, showing boot text.
+    # then restarting display-manager.service gets us to the login.
+    #
+    # NB: the above log is default level. though less specific, there's a `err` level message that also signals this:
+    # sun4i-drm display-engine: failed to bind 1ee0000.hdmi (ops sun8i_dw_hdmi_ops [sun8i_drm_hdmi]): -17
+    # NB: this is the most common, but not the only, failure mode for `display-manager`.
+    # another error seems characterized by these dmesg logs, in which reprobing sun8i_drm_hdmi does not fix:
+    # ```syslog
+    # sun6i-mipi-dsi 1ca0000.dsi: Couldn't get the MIPI D-PHY
+    # sun4i-drm display-engine: Couldn't bind all pipelines components
+    # sun6i-mipi-dsi 1ca0000.dsi: Couldn't register our component
+    # ```
+
+    if (${dmesg} --kernel --level err --color=never --notime | ${grep} -q 'sun4i-drm display-engine: failed to bind 1ee0000.hdmi')
+    then
+      echo "reprobing sun8i_drm_hdmi"
+      # if a command here fails it errors the whole service, so prefer to log instead
+      ${modprobe} -r sun8i_drm_hdmi || echo "failed to unload sun8i_drm_hdmi"
+      ${modprobe} sun8i_drm_hdmi || echo "failed to load sub8i_drm_hdmi"
+    fi
+  '';
+in
 {
   boot.kernelPackages = pkgs.linuxPackagesFor pkgs.linux-megous;
   # boot.kernelPackages = pkgs.linuxPackagesFor pkgs.linux-manjaro;
@@ -25,4 +65,7 @@
     target = "Image.gz";  # <-- compress the kernel image
     # target = "zImage";  # <-- confuses other parts of nixos :-(
   };
+
+  services.xserver.displayManager.job.preStart = ensureHWReady;
+  systemd.services.greetd.preStart = ensureHWReady;
 }