====== SFP GPON ONU EEPROM Editing ======

===== Add 2500Base-X =====

Credit: https://github.com/Anime4000/RTL960x/discussions/250#discussion-6288339

==== Prerequisites ====

  * OpenWrt router with:
    * SFP port(s) (any speed) with I2C bus
    * Packages ''ethtool-full'' ''i2c-tools''

==== Steps ====

  - SSH into OpenWrt
  - Run one of the following commands to determine which I2C bus your SFP is on
    * If your router has **a single SFP**:
      - ''%%BUS=$(for bus in /sys/bus/i2c/devices/i2c-*; do b=${bus##*-}; i2cdetect -y -r $b 2>/dev/null | grep -q " 50 " && i2cdetect -y -r $b 2>/dev/null | grep -q " 51 " && echo $b; done)%%''
      - ''echo $BUS'' and check there is a value before proceeding (you can also run the multiple SFP script below to verify the SFP vendor and S/N)
    * If your router has **multiple SFPs**:
      - <code>for bus in /sys/bus/i2c/devices/i2c-*; do
    b=${bus##*-}
    if i2cdetect -y -r $b 2>/dev/null | grep -q " 50 " && i2cdetect -y -r $b 2>/dev/null | grep -q " 51 "; then
        vendor=""
        for reg in $(seq 20 35); do
            vendor="$vendor$(printf "\\x$(i2cget -y $b 0x50 $reg | sed 's/0x//')")"
        done
        serial=""
        for reg in $(seq 68 83); do
            serial="$serial$(printf "\\x$(i2cget -y $b 0x50 $reg | sed 's/0x//')")"
        done
        echo ""
        echo "Bus: $b"
        echo "├─▶ Vendor: $vendor"
        echo "└─▶ S/N: $serial"
    fi
done</code>
      - Determine the correct bus number, e.g. 5
      - ''BUS=5'' (replace 5 with the respective bus number)
  - Run the following commands to set the SFP EEPROM bits in OpenWrt according to the EEPROM Bits table below
    - ''i2cset -y $BUS 0x50 0x06 0x00''
    - ''i2cset -y $BUS 0x50 0x0a 0x05''
    - ''i2cset -y $BUS 0x50 0x0c 0x1f''
    - ''%%i2cset -y $BUS 0x50 0x3f $(i2cdump -y -r 0-62 $BUS 0x50 b | awk 'NR>1 {for(i=2;i<=NF;i++) if($i~/^[0-9a-f]{2}$/) {cmd="printf \"%d\" 0x"$i; cmd|getline d; close(cmd); sum+=d}} END {printf "0x%02x", sum % 256}')%%''
  - Physically re-seat the SFP
  - Verify the new speeds are detected:\\ ''ethtool -m //**[ethX]**//''\\ <code>
        Supported link modes:   2500baseX/Full
                                1000baseX/Full
</code>

==== EEPROM Bits ====

^  Address  ^  Field  ^  Old Value  ^  New Value  ^  Reason  ^
|  ''0x06''  |  Ethernet Compliance  |  ''0x02''  |  ''0x00''  |  Clear 1000BASE-LX to avoid advertising conflicting speeds alongside 2500BASE-X  |
|  ''0x0A''  |  Extended Compliance  |  ''0x00''  |  ''0x05''  |  Declare 2500BASE-X support  |
|  ''0x0C''  |  Nominal Bit Rate  |  ''0x0D''  |  ''0x1F''  |  Set to 3100MBd (correct value for 2500BASE-X)  |
|  ''0x3F''  |  CC_BASE Checksum  |  (varies)  |  (recalculated by ''awk'')  |  Sum of bytes 0x00–0x3E mod 256  |
|  ''0x5F''  |  CC_EXT Checksum  |  (varies)  |  (unchanged)  |  Not affected by these changes  |

==== EEPROM Bits (XG-PON/XGS-PON) ====

> ⚠️ **Warning:** These settings are untested. Proceed with caution.

Notes:

  * Due to Linux kernel limitations, only a single speed can be advertised via EEPROM for XG-PON/XGS-PON. Multi-rate combinations (e.g. 2.5/5Gbps, 5/10Gbps, 2.5/5/10Gbps) are not achievable through EEPROM editing alone((Linux's SFP bus driver derives supported speeds solely from EEPROM compliance codes, which only allows a single speed to be declared via the compliance code bytes. Multi-rate support requires either a kernel quirk (hardcoded per vendor/part number in ''sfp.c''), a PHY-emulating module that negotiates speeds independently, or a NIC driver that bypasses the generic SFP bus logic entirely.))
  * You do not have to update the 0x5F checksum (CC_EXT) unless you edit addresses ''0x40''–''0x5E'', which are out of scope of this guide; but in case you need it, this command will update CC_EXT:\\ ''%%i2cset -y $BUS 0x50 0x5f $(i2cdump -y -r 64-94 $BUS 0x50 b | awk 'NR>1 {for(i=2;i<=NF;i++) if($i~/^[0-9a-f]{2}$/) {cmd="printf \"%d\" 0x"$i; cmd|getline d; close(cmd); sum+=d}} END {printf "0x%02x", sum % 256}')%%''

=== Fiber Rates (No PHY) ===

^  Address  ^  Field  ^  Choose only ONE column of values  ^^^^^^
^  :::  ^  :::  ^  1000BASE-X  ^  2500BASE-X  ^  10GBASE-LR  ^  10GBASE-SR  ^  10GBASE-LRM  ^  10GBASE-ER  ^
|  ''0x03''  |  10G Ethernet Compliance  |  ''0x00''  |  ''0x00''  |  ''0x20''  |  ''0x10''  |  ''0x40''  |  ''0x80''  |
|  ''0x06''  |  Ethernet Compliance  |  ''0x02''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |
|  ''0x0A''  |  Extended Compliance  |  ''0x00''  |  ''0x05''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |
|  ''0x0C''  |  Nominal Bit Rate  |  ''0x0D'' (1300MBd)  |  ''0x1F'' (3100MBd)  |  ''0x67'' (10300MBd)  |  ''0x67'' (10300MBd)  |  ''0x67'' (10300MBd)  |  ''0x67'' (10300MBd)  |
|  ''0x3F''  |  CC_BASE Checksum  |  (recalculated by ''awk'')  ||||||

Notes:

  * Set ''0x06'' to ''0x00'' (clear 1000BASE-LX) for all configurations above except 1000BASE-X, to avoid advertising conflicting speeds alongside the selected rate

=== Copper Rates (PHY Emulation Required) ===

^  Address  ^  Field  ^  Choose only ONE column of values  ^^^^
^  :::  ^  :::  ^  2500BASE-T  ^  5GBASE-T  ^  10GBASE-T (SFI)  ^  10GBASE-T (SR, 30m)  ^
|  ''0x03''  |  10G Ethernet Compliance  |  ''0x00''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |
|  ''0x06''  |  Ethernet Compliance  |  ''0x00''  |  ''0x00''  |  ''0x00''  |  ''0x00''  |
|  ''0x0A''  |  Extended Compliance  |  ''0x1E''  |  ''0x1D''  |  ''0x16''  |  ''0x1C''  |
|  ''0x0C''  |  Nominal Bit Rate  |  ''0x1F'' (3100MBd)  |  ''0x32'' (5000MBd)  |  ''0x67'' (10300MBd)  |  ''0x67'' (10300MBd)  |
|  ''0x3F''  |  CC_BASE Checksum  |  (recalculated by ''awk'')  ||||