efc: add link recal section

src/hw/efc.md

@@ -81,6 +81,15 @@ Kasli Satellite(SFP0)(DEST0). EFC is connected to Kasli Satellite with DRTIO ove
 When you are building a crate with EFC(s), you should erase the flash/SD card config on both the EFC and
 Kasli/Kasli-SoC. Always flash the EFC Board first before flashing the Kasli/Kasli-SoC.
 
+Use the Digilent HS2 JTAG adapter connected to the JTAG port on the EFC, located next to the barrel jack.
+
+To flash the gateware and firmware onto the EFC board,
+```shell
+artiq_flash --srcbuild -t [efc1v0, efc1v1] -d artiq_efc/EFC
+```
+
+## Link recalibration
+
 If either of the following elements is changed, you will need to **ERASE** the stored calibrated values on both
 the EFC and Kasli Master, or the communication between the boards cannot be established:
 
@@ -90,19 +99,12 @@ the EFC and Kasli Master, or the communication between the boards cannot be esta
 4. Kasli/Kasli-SoC Master Gateware
 5. EFC Board/Kasli/Kasli-SoC PCB
 
-Use the Digilent HS2 JTAG adapter connected to the JTAG port on the EFC, located next to the barrel jack.
+To recalibrate the link delay, erase the calibrated value on all cards in the same power cycle:
 
-To erase the flash on the EFC board,
+- EFC: connect the JTAG port and run `artiq_flash erase=storage -t efc`
+- Kasli: connect the USB port and run `artiq_flash erase=storage -t kasli`
+- Kasli-SoC: remove `eem_drtio_delay{n}` line in the SD card `Config` file
 
-```shell
-artiq_flash -t efc erase
-```
-
-To flash the gateware and firmware onto the EFC board, ,
-
-```shell
-artiq_flash --srcbuild -t [efc1v0, efc1v1] -d artiq_efc/EFC
-```
 
 ## UART log access