[openwrt/openwrt] ath79: mikrotik: erase firmware on SPI NOR before install

[LEDE Commits]

adrian pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/2cac31223d97fffacb8154f5739c67dfe078106f

commit 2cac31223d97fffacb8154f5739c67dfe078106f
Author: Thibaut VARÈNE <hacks at slashdirt.org>
AuthorDate: Mon Aug 17 12:44:13 2020 +0200

    ath79: mikrotik: erase firmware on SPI NOR before install
    
    On Mikrotik SPI NOR devices, the firmware partition must be erased when
    flashing from stock firmware, otherwise leftover bits (in particular a
    kernel signature) can trigger a boot loop.
    
    When booted from initramfs (the only way to install OpenWRT on these
    devices), this patch unconditionally erases the firmware partition in
    the do_upgrade() stage for all supported SPI NOR devices.
    
    This is forward-ported from ed49d0876 and 20452a8db
    
    Signed-off-by: Thibaut VARÈNE <hacks at slashdirt.org>
---
 target/linux/ath79/mikrotik/base-files/lib/upgrade/platform.sh | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/target/linux/ath79/mikrotik/base-files/lib/upgrade/platform.sh b/target/linux/ath79/mikrotik/base-files/lib/upgrade/platform.sh
index d79bd03af5..5ee5492369 100644
--- a/target/linux/ath79/mikrotik/base-files/lib/upgrade/platform.sh
+++ b/target/linux/ath79/mikrotik/base-files/lib/upgrade/platform.sh
@@ -38,6 +38,9 @@ platform_do_upgrade() {
 		platform_do_upgrade_mikrotik_nand "$1"
 		;;
 	*)
+		# NOR devices: erase firmware if booted from initramfs
+		[ -z "$(rootfs_type)" ] && mtd erase firmware
+
 		default_do_upgrade "$1"
 		;;
 	esac