openwrt/target/linux/ramips/patches-6.6/314-MIPS-add-bootargs-override-property.patch

From f15d27f9c90ede4b16eb37f9ae573ef81c2b6996 Mon Sep 17 00:00:00 2001
From: David Bauer <mail@david-bauer.net>
Date: Thu, 31 Dec 2020 18:49:12 +0100
Subject: [PATCH] MIPS: add bootargs-override property

Add support for the bootargs-override property to the chosen node
similar to the one used on ipq806x or mpc85xx.

This is necessary, as the U-Boot used on some boards, notably the
Ubiquiti UniFi 6 Lite, overwrite the bootargs property of the chosen
node leading to a kernel panic when loading OpenWrt.

Signed-off-by: David Bauer <mail@david-bauer.net>
---
 arch/mips/kernel/setup.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -564,8 +564,28 @@ static int __init bootcmdline_scan_chose
 
 #endif /* CONFIG_OF_EARLY_FLATTREE */
 
+static int __init bootcmdline_scan_chosen_override(unsigned long node, const char *uname,
+						   int depth, void *data)
+{
+	bool *dt_bootargs = data;
+	const char *p;
+	int l;
+
+	if (depth != 1 || !data || strcmp(uname, "chosen") != 0)
+		return 0;
+
+	p = of_get_flat_dt_prop(node, "bootargs-override", &l);
+	if (p != NULL && l > 0) {
+		strlcpy(boot_command_line, p, COMMAND_LINE_SIZE);
+		*dt_bootargs = true;
+	}
+
+	return 1;
+}
+
 static void __init bootcmdline_init(void)
 {
+	bool dt_bootargs_override = false;
 	bool dt_bootargs = false;
 
 	/*
@@ -579,6 +599,14 @@ static void __init bootcmdline_init(void
 	}
 
 	/*
+	 * If bootargs-override in the chosen node is set, use this as the
+	 * command line
+	 */
+	of_scan_flat_dt(bootcmdline_scan_chosen_override, &dt_bootargs_override);
+	if (dt_bootargs_override)
+		return;
+
+	/*
 	 * If the user specified a built-in command line &
 	 * MIPS_CMDLINE_BUILTIN_EXTEND, then the built-in command line is
 	 * prepended to arguments from the bootloader or DT so we'll copy them