hikey_debian: Add notes to try 'make recovery' if 'make flash' fails

Signed-off-by: Victor Chong <victor.chong@linaro.org>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
diff --git a/docs/hikey.md b/docs/hikey.md
index c863f9b..811cdcf 100644
--- a/docs/hikey.md
+++ b/docs/hikey.md
@@ -78,7 +78,10 @@
 ```
 
 The `make flash` step will tell you how you should set the jumpers on the board
-and how to flash the device.
+and how to flash the device. There have been reports of some boards stalling or
+getting stuck in `make flash` when flashing `SYSTEM_IMG`, i.e. the command does
+not complete after more than 5 minutes. If that happens, please try running
+`make recovery` instead.
 
 Now you can boot up the device, note that the **up-to-date** OP-TEE normal world
 binaries still hasn't been put on the device at this stage. So by now you're
diff --git a/hikey_debian.mk b/hikey_debian.mk
index 1cb8de0..19b58c5 100644
--- a/hikey_debian.mk
+++ b/hikey_debian.mk
@@ -358,6 +358,9 @@
 	@echo "    \"Android Fastboot mode - version x.x Press any key to quit.\""
 	@read -r -p "   Then press any key to continue flashing" dummy
 endif
+	@echo "If the board stalls while flashing $(SYSTEM_IMG),"
+	@echo "i.e. does not complete after more than 5 minutes,"
+	@echo "please try running 'make recovery' instead"
 	fastboot flash ptable $(LLOADER_PATH)/ptable-linux-$(CFG_FLASH_SIZE)g.img
 	fastboot flash fastboot $(ARM_TF_PATH)/build/hikey/$(ARM_TF_BUILD)/fip.bin
 	fastboot flash nvme $(NVME_IMG)