--- zzzz-none-000/linux-3.10.107/arch/mips/lantiq/prom.c	2017-06-27 09:49:32.000000000 +0000
+++ vr9-7490-729/linux-3.10.107/arch/mips/lantiq/prom.c	2021-11-10 11:53:54.000000000 +0000
@@ -12,6 +12,8 @@
 #include <linux/of_platform.h>
 #include <linux/of_fdt.h>
 
+#include <linux/avm_kernel_config.h>
+
 #include <asm/bootinfo.h>
 #include <asm/time.h>
 
@@ -39,7 +41,7 @@
 {
 }
 
-static void __init prom_init_cmdline(void)
+void __init prom_init_cmdline(void)
 {
 	int argc = fw_arg0;
 	char **argv = (char **) KSEG1ADDR(fw_arg1);
@@ -70,6 +72,39 @@
 	 * Load the builtin devicetree. This causes the chosen node to be
 	 * parsed resulting in our memory appearing
 	 */
+
+	if (IS_ENABLED(CONFIG_AVM_ENHANCED)) {
+		char *subrev_str;
+		int subrev = 0;
+
+		subrev_str = prom_getenv("HWSubRevision");
+		if (subrev_str) {
+			if (sscanf(subrev_str, "%u", &subrev) != 1)
+				subrev_str = NULL;
+		}
+		if (!subrev_str) {
+			pr_emerg("%s: Unable to read AVM hardware "
+				 "subrevision! Identity crisis... who am I?",
+				 __func__);
+		}
+
+		pr_emerg("%s: AVM hardware subrevision %d\n", __func__,
+			 subrev);
+
+		if (subrev > avm_subrev_max) {
+			pr_emerg("%s: Too many hardware subrevisions!\n", __func__);
+			panic();
+		}
+
+		__dtb_start = avm_kernel_config_device_tree[subrev];
+
+		if (!__dtb_start) {
+			pr_emerg("%s: Missing device-tree for AVM hardware "
+				 "subrevision %d\n", __func__, subrev);
+			panic();
+		}
+	}
+
 	__dt_setup_arch(&__dtb_start);
 }