diff --git a/.github/workflows/build_pru_gcc.yml b/.github/workflows/build_pru_gcc.yml
index e8cdd81d..a1a92fc1 100644
--- a/.github/workflows/build_pru_gcc.yml
+++ b/.github/workflows/build_pru_gcc.yml
@@ -78,9 +78,3 @@ jobs:
           make PROTO=SBW
           ${{ env.PRU_GCC }}/bin/pru-size gen_gcc/pru0-programmer-SBW-fw.elf
         working-directory: "software/firmware/pru0-programmer/"
-
-      - name: Build Sync (GPIO-Event) 🧱
-        run: |
-          make
-          ${{ env.PRU_GCC }}/bin/pru-size gen_gcc/pru1-sync-fw.elf
-        working-directory: "software/firmware/pru1-sync/"
diff --git a/deploy/roles/maintenance/defaults/main.yml b/deploy/roles/maintenance/defaults/main.yml
index 92c53eaf..5ed235f5 100644
--- a/deploy/roles/maintenance/defaults/main.yml
+++ b/deploy/roles/maintenance/defaults/main.yml
@@ -7,6 +7,6 @@ maintenance_delete_unused_files: true
 
 # rule config
 maintenance_default_kernel: lts-4_19
-maintenance_kernel_pin: "linux-image-4.19.94-ti-rt-r74"  # 2023-10-02: r74 was newest
-# RT -> wanted for ptp and phc2sys (more reliable)
+maintenance_kernel_pin: "linux-image-4.19.94-ti-r74"  # 2024-04-27: r74 was newest
+# -rt -> used for more reliable ptp & gpio-triggering, BUT communication with PRU fails
 maintenance_timezone: Europe/Berlin
diff --git a/software/kernel-module/src/pru_sync_control.c b/software/kernel-module/src/pru_sync_control.c
index 105c3f47..c410eda1 100644
--- a/software/kernel-module/src/pru_sync_control.c
+++ b/software/kernel-module/src/pru_sync_control.c
@@ -200,7 +200,8 @@ int sync_init(uint32_t timer_period_ns)
     trigger_loop_period_kt = ns_to_ktime(trigger_loop_period_ns);
     //printk(KERN_INFO "shprd.k: new timer_period_ns = %u", trigger_loop_period_ns);
 
-    hrtimer_init(&trigger_loop_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS_HARD);
+    hrtimer_init(&trigger_loop_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
+    // TODO: HRTIMER_MODE_ABS_HARD wanted, but _HARD not defined in 4.19 (without -RT)
     trigger_loop_timer.function = &trigger_loop_callback;
 
     /* timer for Sync-Loop */
@@ -208,7 +209,7 @@ int sync_init(uint32_t timer_period_ns)
     sync_loop_timer.function = &sync_loop_callback;
 
     init_done                = 1;
-    printk(KERN_INFO "shprd.k: pru-sync-system initialized");
+    printk(KERN_INFO "shprd.k: pru-sync-system initialized (wanted: hres, abs, hard)");
 
     printk(KERN_INFO "shprd.k: trigger_hrtimer.hres    = %d",
            hrtimer_is_hres_active(&trigger_loop_timer));
@@ -268,7 +269,7 @@ void sync_start(void)
     }
 
     hrtimer_start(&trigger_loop_timer, ts_now_kt + ns_to_ktime(ns_to_next_trigger),
-                  HRTIMER_MODE_ABS_HARD);
+                  HRTIMER_MODE_ABS);  // was: HRTIMER_MODE_ABS_HARD for -rt Kernel
 
     hrtimer_start(&sync_loop_timer, ts_now_kt + ns_to_ktime(1000000), HRTIMER_MODE_ABS);
     printk(KERN_INFO "shprd.k: pru-sync-system started");