[openwrt/openwrt] mvebu: sysupgrade: drop unnecessary UBI to UBI logic

[LEDE Commits]

chunkeey pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/0efb169aadc868768fde4a22c3be8a3742f73dbe

commit 0efb169aadc868768fde4a22c3be8a3742f73dbe
Author: Bjørn Mork <bjorn at mork.no>
AuthorDate: Sat Mar 20 11:48:24 2021 +0100

    mvebu: sysupgrade: drop unnecessary UBI to UBI logic
    
    The recent changes to the maximum kernel size for Mamba and Venom
    highlighted the fact that the old Mamba kernel size has been
    hardcoded in linksys_get_root_magic() even for devices with
    a different kernel/rootfs split.
    
    The purpose of this code seems to be to avoid issues caused
    by partially overwriting an existing UBI partition, where some
    of the erase counters would be reset but not the unmodified
    ones.  This problem has been solved in a more generic way by
    the UBI EOF marker. This ensures that any old PEBs after the
    marker are properly initialized.  It is therefore unnecessary
    to erase the whole partition before flashing a new OpenWrt
    factory image.
    
    Signed-off-by: Bjørn Mork <bjorn at mork.no>
---
 .../mvebu/cortexa9/base-files/lib/upgrade/linksys.sh  | 19 +------------------
 1 file changed, 1 insertion(+), 18 deletions(-)

diff --git a/target/linux/mvebu/cortexa9/base-files/lib/upgrade/linksys.sh b/target/linux/mvebu/cortexa9/base-files/lib/upgrade/linksys.sh
index c5da471d76..aaa32eb4ea 100644
--- a/target/linux/mvebu/cortexa9/base-files/lib/upgrade/linksys.sh
+++ b/target/linux/mvebu/cortexa9/base-files/lib/upgrade/linksys.sh
@@ -44,10 +44,6 @@ linksys_get_target_firmware() {
 	esac
 }
 
-linksys_get_root_magic() {
-	(get_image "$@" | dd skip=786432 bs=4 count=1 | hexdump -v -n 4 -e '1/1 "%02x"') 2>/dev/null
-}
-
 platform_do_upgrade_linksys() {
 	local magic_long="$(get_magic_long "$1")"
 
@@ -75,20 +71,7 @@ platform_do_upgrade_linksys() {
 		nand_upgrade_tar "$1"
 	}
 	[ "$magic_long" = "27051956" -o "$magic_long" = "0000a0e1" ] && {
-		# check firmwares' rootfs types
-		local target_mtd=$(find_mtd_part $part_label)
-		local oldroot="$(linksys_get_root_magic $target_mtd)"
-		local newroot="$(linksys_get_root_magic "$1")"
-
-		if [ "$newroot" = "55424923" -a "$oldroot" = "55424923" ]
-		# we're upgrading from a firmware with UBI to one with UBI
-		then
-			# erase everything to be safe
-			mtd erase $part_label
-			get_image "$1" | mtd -n write - $part_label
-		else
-			get_image "$1" | mtd write - $part_label
-		fi
+		get_image "$1" | mtd write - $part_label
 	}
 }