substantially bump the helper timeout

its running time entirely depends on how fast the initrds are
to generate and how many there are. 60 seconds may not be nearly
enough.

BUG: 400641

src/helper.cpp

 /*
- *  SPDX-FileCopyrightText: 2021 Harald Sitter <sitter@kde.org>
+ *  SPDX-FileCopyrightText: 2021-2022 Harald Sitter <sitter@kde.org>
  *  SPDX-FileCopyrightText: 2016 Marco Martin <mart@kde.org>
  *  SPDX-FileCopyrightText: 1998 Luca Montecchiani <m.luca@usa.net>
  *
@@ -159,7 +159,10 @@ ActionReply PlymouthHelper::save(const QVariantMap &args)
         reply.setErrorDescription(i18n("Cannot start initramfs."));
         return reply;
     }
-    if (!process.waitForFinished(std::chrono::milliseconds(1min).count())) {
+    // We don't know how long this will take. The helper will need to generate N=installed_kernels initrds.
+    // Be very generous with the timeout! https://bugs.kde.org/show_bug.cgi?id=400641
+    // NB: there is also a timeout in the KCM
+    if (!process.waitForFinished(std::chrono::milliseconds(15min).count())) {
         reply = ActionReply::BackendError;
         reply.setErrorDescription(i18n("Initramfs failed to run."));
         return reply;

src/kcm.cpp

 /*
  *  SPDX-FileCopyrightText: 2017 Marco Martin <mart@kde.org>
  *  SPDX-FileCopyrightText: 2014 Vishesh Handa <me@vhanda.in>
+ *  SPDX-FileCopyrightText: 2022 Harald Sitter <sitter@kde.org>
  *
  *  SPDX-License-Identifier: GPL-2.0-or-later
  *
@@ -9,6 +10,8 @@
 #include "kcm.h"
 #include "config-kcm.h"
 
+#include <chrono>
+
 #include <KAboutData>
 #include <KConfigGroup>
 #include <KPluginFactory>
@@ -32,6 +35,8 @@
 #include <KIO/CopyJob>
 #include <kio/job.h>
 
+using namespace std::chrono_literals;
+
 K_PLUGIN_FACTORY_WITH_JSON(KCMPlymouthFactory, "kcm_plymouth.json", registerPlugin<KCMPlymouth>();)
 
 KCMPlymouth::KCMPlymouth(QObject *parent, const QVariantList &args)
@@ -193,7 +198,10 @@ void KCMPlymouth::save()
     KAuth::Action action(authActionName());
     action.setHelperId(QStringLiteral("org.kde.kcontrol.kcmplymouth"));
     action.setArguments(helperargs);
-    action.setTimeout(60000);
+    // We don't know how long this will take. The helper will need to generate N=installed_kernels initrds.
+    // Be very generous with the timeout! https://bugs.kde.org/show_bug.cgi?id=400641
+    // NB: there is also a timeout in the helper
+    action.setTimeout(std::chrono::milliseconds(15min).count());
 
     KAuth::ExecuteJob *job = action.execute();
     bool rc = job->exec();