[openwrt/openwrt] mediatek: mt7622: bpi-r64: fix sysupgrade on empty disk

[LEDE Commits]

dangole pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/2151d897135501b9515ac0674e36ec79ae949ab8

commit 2151d897135501b9515ac0674e36ec79ae949ab8
Author: Daniel Golle <daniel at makrotopia.org>
AuthorDate: Mon Mar 1 19:31:51 2021 +0000

    mediatek: mt7622: bpi-r64: fix sysupgrade on empty disk
    
    Signed-off-by: Daniel Golle <daniel at makrotopia.org>
---
 target/linux/mediatek/mt7622/base-files/lib/upgrade/platform.sh | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/target/linux/mediatek/mt7622/base-files/lib/upgrade/platform.sh b/target/linux/mediatek/mt7622/base-files/lib/upgrade/platform.sh
index 07efe13363..4e45c026ab 100755
--- a/target/linux/mediatek/mt7622/base-files/lib/upgrade/platform.sh
+++ b/target/linux/mediatek/mt7622/base-files/lib/upgrade/platform.sh
@@ -16,6 +16,13 @@ get_rootdev() {
 	local rootvol rootdev
 	rootvol=$(get_cmdline_var root)
 	rootvol=$(basename $rootvol)
+	[ -e /sys/class/block/$rootvol ] || {
+		rootvol=${rootvol%%[0-9]}
+		[ -e /sys/class/block/$rootvol ] && echo $rootvol
+		rootvol=${rootvol%%p}
+		[ -e /sys/class/block/$rootvol ] && echo $rootvol
+		return
+	}
 	[ -e /sys/class/block/$rootvol/partition ] || {
 		echo $rootvol
 		return
@@ -89,13 +96,13 @@ platform_check_image() {
 }
 
 platform_copy_config_mmc() {
+	[ -e "$UPGRADE_BACKUP" ] || return
 	local rootdev=$(cat /tmp/sysupgrade.rootdev)
 	blockdev --rereadpt /dev/$rootdev
 	local datadev=$(get_partition $rootdev rootfs_data)
 	[ "$datadev" ] || echo "no rootfs_data partition, cannot keep configuration." >&2
 	dd if="$UPGRADE_BACKUP" of=/dev/$datadev
 	sync
-	sleep 4
 }
 
 platform_copy_config() {