--- zzzz-none-000/linux-3.10.107/lib/decompress.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/lib/decompress.c	2021-02-04 17:41:59.000000000 +0000
@@ -11,10 +11,12 @@
 #include <linux/decompress/unxz.h>
 #include <linux/decompress/inflate.h>
 #include <linux/decompress/unlzo.h>
+#include <linux/decompress/unlz4.h>
 
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/init.h>
+#include <linux/printk.h>
 
 #ifndef CONFIG_DECOMPRESS_GZIP
 # define gunzip NULL
@@ -31,6 +33,9 @@
 #ifndef CONFIG_DECOMPRESS_LZO
 # define unlzo NULL
 #endif
+#ifndef CONFIG_DECOMPRESS_LZ4
+# define unlz4 NULL
+#endif
 
 struct compress_format {
 	unsigned char magic[2];
@@ -39,22 +44,29 @@
 };
 
 static const struct compress_format compressed_formats[] __initconst = {
-	{ {037, 0213}, "gzip", gunzip },
-	{ {037, 0236}, "gzip", gunzip },
+	{ {0x1f, 0x8b}, "gzip", gunzip },
+	{ {0x1f, 0x9e}, "gzip", gunzip },
 	{ {0x42, 0x5a}, "bzip2", bunzip2 },
 	{ {0x5d, 0x00}, "lzma", unlzma },
+	{ {0x6d, 0x00}, "lzma-openwrt", unlzma },
 	{ {0xfd, 0x37}, "xz", unxz },
 	{ {0x89, 0x4c}, "lzo", unlzo },
+	{ {0x02, 0x21}, "lz4", unlz4 },
 	{ {0, 0}, NULL, NULL }
 };
 
-decompress_fn __init decompress_method(const unsigned char *inbuf, int len,
+decompress_fn __init decompress_method(const unsigned char *inbuf, long len,
 				const char **name)
 {
 	const struct compress_format *cf;
 
-	if (len < 2)
+	if (len < 2) {
+		if (name)
+			*name = NULL;
 		return NULL;	/* Need at least this much... */
+	}
+
+	pr_debug("Compressed data magic: %#.2x %#.2x\n", inbuf[0], inbuf[1]);
 
 	for (cf = compressed_formats; cf->name; cf++) {
 		if (!memcmp(inbuf, cf->magic, 2))