From: Hans de Goede <hansg@kernel.org>
Date: Tue, 1 Jul 2025 18:41:24 +0000 (+0200)
Subject: Add UseSimpledrmNoLuks config file keyword
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d7b43158c9d0242933a925f0571b97f0e28c4df9;p=thirdparty%2Fplymouth.git

Add UseSimpledrmNoLuks config file keyword

Add a UseSimpledrmNoLuks config file keyword this enables simpledrm use,
like the existing "UseSimpledrm" config file keyword. Except when using
LUKS. Showing the LUKS unlock screen using simpledrm has 2 problems:

1. If the GPU drivers are built into the initrd then typically the
   unlock screen will briefly show and then the screen goes black

2. The i915 driver uses the firmware framebuffer as fallback when
   userspace has not installed a fb to scan out from. This happens
   e.g. on logout between the user-session and the display-manager.
   Drawing the unlock screen on the simpledrm fb results in it briefly
   showing when logging out, which looks quite ugly.

This allows distributions to chose to only enable simpledrm when
LUKS is not used.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=2359283
Signed-off-by: Hans de Goede <hansg@kernel.org>
---

diff --git a/src/main.c b/src/main.c
index d9ba7340..320fa965 100644
--- a/src/main.c
+++ b/src/main.c
@@ -343,6 +343,29 @@ load_settings (state_t    *state,
         if (state->use_simpledrm == -1)
                 state->use_simpledrm = ply_key_file_get_ulong (key_file, "Daemon", "UseSimpledrm", -1);
 
+        /*
+         * Check the special UseSimpledrmNoLuks config file keyword this enables
+         * simpledrm use except when using LUKS. Showing the LUKS unlock screen
+         * using simpledrm has 2 problems:
+         * 1. If the GPU drivers are built into the initrd then typically the
+         *    unlock screen will briefly show and then the screen goes black
+         *    while the native GPU driver loads leading to a jarring experience.
+         * 2. The i915 driver uses the firmware framebuffer as fallback when
+         *    userspace has not installed a fb to scan out from. This happens
+         *    e.g. on logout between the user-session and the display-manager.
+         *    Drawing the unlock screen on the simpledrm fb results in it briefly
+         *    showing when logging out, which looks quite ugly. Also see:
+         *    https://bugzilla.redhat.com/show_bug.cgi?id=2359283
+         */
+        if (state->use_simpledrm == -1) {
+                state->use_simpledrm = ply_key_file_get_ulong (key_file, "Daemon", "UseSimpledrmNoLuks", -1);
+                if (state->use_simpledrm != -1 &&
+                    ply_kernel_command_line_get_string_after_prefix ("rd.luks.uuid=")) {
+                        ply_trace ("Ignoring UseSimpledrmNoLuks because of LUKS use");
+                        state->use_simpledrm = -1;
+                }
+        }
+
         settings_loaded = true;
 out:
         free (splash_string);