ramips: add support for Xiaomi Mi Router 4AC (100M Edition)

[Sorin Pop]

It seems that the difference is not that it's 4AC because even the one
in OpenWrt ATM is a 4AC (defined as 4A) but what I found out is that
4AC seem to have 2 different versions/flavors:
    * 4AC CN -> It's using CPU at 380MHz and the bootloader entry point
is bc160000 and limits the WiFi to 20dBm for 2.4GHz and 20dBm for 5GHz
(Currently in OpenWRT)
    * 4AC EU(or International) -> It's using CPU at 375MHz and the
bootloader entry point is bc260000 and limits the WiFi to 16dBm for
2.4GHz and 18dBm for 5GHz

If I update the bootloader and factory partitions on a EU version with
the CN version it increases the WiFi limits, increases the CPU MHz and
changes the entry point. Using the 160000 entry point is better as we
have more available space, but we would need to create a custom U-Boot
bootloader (and I have no experience there).

Sorin


On Tue, Dec 8, 2020 at 5:19 PM Adrian Schmutzler
<mail at adrianschmutzler.de> wrote:
>
> > -----Original Message-----
> > From: openwrt-devel [mailto:openwrt-devel-bounces at lists.openwrt.org]
> > On Behalf Of Sorin Pop
> > Sent: Sonntag, 6. Dezember 2020 02:06
> > To: Adrian Schmutzler <mail at adrianschmutzler.de>
> > Cc: openwrt-devel at lists.openwrt.org
> > Subject: Re: ramips: add support for Xiaomi Mi Router 4AC (100M Edition)
> >
> > The difference is the size of the overlay and partition table and the uboot
> > that is used on the devices.
> >
> > xiaomi_mir4a-100m uses bc160000 as entry point and xiaomi_mir4ac-100m
> > uses bc260000 as entry point
> >
> > from what I have seen mir4a is a CN version of MIR4AC which is EU.
>
> And could you please check whether this runs with spi-max-frequency = 40 MHz like mi-router-4c does?
>
> Best
>
> Adrian
>
> >
> > On Sun, Dec 6, 2020 at 2:38 AM Adrian Schmutzler
> > <mail at adrianschmutzler.de> wrote:
> > >
> > > > -----Original Message-----
> > > > From: openwrt-devel [mailto:openwrt-devel-
> > bounces at lists.openwrt.org]
> > > > On Behalf Of Sorin Pop
> > > > Sent: Sonntag, 6. Dezember 2020 00:54
> > > > To: openwrt-devel at lists.openwrt.org
> > > > Subject: ramips: add support for Xiaomi Mi Router 4AC (100M Edition)
> > > >
> > > > - SoC:      MediaTek MT7628AN
> > > > - Flash:    16MB (Winbond W25Q128JV)
> > > > - RAM:      64MB
> > > > - Serial:   As marked on PCB, 3V3 logic, baudrate is 115200
> > > > - Ethernet: 3x 10/100 Mbps (switched, 2x LAN + WAN)
> > > > - WIFI0:    MT7628AN 2.4GHz 802.11b/g/n
> > > > - WIFI1:    MT7612EN 5GHz 802.11ac
> > > > - Antennas: 4x external (2 per radio), non-detachable
> > > > - LEDs:     Programmable power-LED (two-colored, yellow/blue)
> > > >             Non-programmable internet-LED (shows WAN-activity)
> > > > - Buttons:  Reset
> > >
> > > So, the only difference in implementation is the size of overlay/firmware
> > partitions?
> > >
> > > Best
> > >
> > > Adrian
> > >
> > > >
> > > > INSTALLATION:
> > > >
> > > > 1. Connect to the serial port of the router and power it up.
> > > >    If you get a prompt asking for boot-mode, go to step 3.
> > > > 2. Unplug the router after
> > > >        > Erasing SPI Flash...
> > > >        > raspi_erase: offs:20000 len:10000
> > > >    occurs on the serial port. Plug the router back in.
> > > > 3. At the prompt select option 2 (Load system code then
> > > >    write to Flash via TFTP.)
> > > > 4. Enter 192.168.1.1 as the device IP and 192.168.1.2 as the
> > > >    Server-IP.
> > > > 5. Connect your computer to LAN1 and assign it as 192.168.1.2/24.
> > > > 6. Serve the sysupgrade image via TFTP
> > > >
> > > > This router seems to have the same hardware as Xiaomi Mi Router 4A
> > > > (100M
> > > > Edition) but it uses a different U-Boot.
> > > >
> > > > Signed-off-by: Sorin Pop <alexsorinpop at gmail.com>
> >
> >
> >
> > --
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