Davide Fioravanti 31b49f02ca ramips: add support for Linksys EA7500 v2 ... The Linksys EA7500 v2 is advertised as AC1900, but its internal hardware is AC2600 capable. Hardware -------- SoC: Mediatek MT7621AT (880 MHz, 2 cores 4 threads) RAM: 256M (Nanya NT5CC128M16IP-DI) FLASH: 128MB NAND (Macronix MX30LF1G18AC-TI) ETH: 5x 10/100/1000 Mbps Ethernet (MT7530) WIFI: - 2.4GHz: 1x MT7615N (4x4:4) - 5GHz: 1x MT7615N (4x4:4) - 4 antennas: 3 external detachable antennas and 1 internal USB: - 1x USB 3.0 - 1x USB 2.0 BTN: - 1x Reset button - 1x WPS button LEDS: - 1x White led (Power) - 6x Green leds (link lan1-lan4, link wan, wps) - 5x Orange leds (act lan1-lan4, act wan) (working but unmodifiable) Everything works correctly. Installation ------------ The “factory” openwrt image can be flashed directly from OEM stock firmware. After the flash the router will reboot automatically. However, due to the dual boot system, the first installation could fail (if you want to know why, read the footnotes). If the flash succeed and you can reach OpenWrt through the web interface or ssh, you are done. Otherwise the router will try to boot 3 times and then will automatically boot the OEM firmware (don’t turn off the router. Simply wait and try to reach the router through the web interface every now and then, it will take few minutes). After this, you should be back in the OEM firmware. Now you have to flash the OEM Firmware over itself using the OEM web interface (I tested it using the FW_EA7500v2_2.0.8.194281_prod.img downloaded from the Linksys website). When the router reboots flash the “factory” OpenWrt image and this time it should work. After the OpenWrt installation you have to use the sysupgrade image for future updates. Restore OEM Firmware -------------------- After the OpenWrt flash, the OEM firmware is still stored in the second partition thanks to the dual boot system. You can switch from OpenWrt to OEM firmware and vice-versa failing the boot 3 times in a row: 1) power on the router 2) wait 15 seconds 3) power off the router 4) repeat steps 1-2-3 twice more. 5) power on the router and you should be in the “other” firmware If you want to completely remove OpenWrt from your router, switch to the OEM firmware and then flash OEM firmware from the web interface as a normal update. This procedure will overwrite the OpenWrt partition. Footnotes --------- The Linksys EA7500-v2 has a dual boot system to avoid bricks. This system works using 2 pair of partitions: 1) "kernel" and "rootfs" 2) "alt_kernel" and "alt_rootfs". After 3 failed boot attempts, the bootloader tries to boot the other pair of partitions and so on. This system is managed by the bootloader, which writes a bootcount in the s_env partition, and if successfully booted, the system add a "zero-bootcount" after the previous value. A system update performed from OEM firmware, writes the firmware on the other pair of partitions and sets the bootloader to boot the new pair of partitions editing the “boot_part” variable in the bootloader vars. Effectively it's a quick and safe system to switch the selected boot partition. Another way to switch the boot partition is: 1) power on the router 2) wait 15 seconds 3) power off the router 4) repeat steps 1-2-3 twice more. 5) power on the router and you should be in the “other” firmware In this OpenWrt port, this dual boot system is partially working because the bootloader sets the right rootfs partition in the cmdline but unfortunately OpenWrt for ramips platform overwrites the cmdline so is not possible to detect the right rootfs partition. Because all of this, I preferred to simply use the first pair of partitions and set read-only the other pair. However this solution is not optimal because is not possible to know without opening the case which is the current booted partition. Let’s take for example a router booting the OEM firmware from the first pair of partitions. If we flash the OpenWrt image, it will be written on the second pair. In this situation the router will bootloop 3 times and then will automatically come back to the first pair of partitions containg the OEM firmware. In this situation, to flash OpenWrt correctly is necessary to switch the booting partition, flashing again the OEM firmware over itself. At this point the OEM firmware is on both pair of partitions but the current booted pair is the second one. Now, flashing the OpenWrt factory image will write the firmware on the first pair and then will boot correctly. If this limitation in the ramips platform about the cmdline will be fixed, the dual boot system can also be implemented in OpenWrt with almost no effort. Signed-off-by: Davide Fioravanti <pantanastyle@gmail.com> Co-Developed-by: Jackson Lim <jackcolentern@gmail.com> Signed-off-by: Jackson Lim <jackcolentern@gmail.com>		2020-05-17 18:44:28 +02:00
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ieee80211	ramips: add support for Linksys EA7500 v2	2020-05-17 18:44:28 +02:00