From 457663fc5157bc37f9b9761199624f690a9e0394 Mon Sep 17 00:00:00 2001
From: Andrew Leech <andrew.leech@planetinnovation.com.au>
Date: Wed, 6 Nov 2024 10:31:28 +1100
Subject: [PATCH] py/mkrules.mk: Use partial clone for submodules if available.

Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>
---
 py/mkrules.mk | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/py/mkrules.mk b/py/mkrules.mk
index 0dc1cdfe15ac4..0ac0d4c76eea8 100644
--- a/py/mkrules.mk
+++ b/py/mkrules.mk
@@ -252,7 +252,11 @@ submodules:
 	$(ECHO) "Updating submodules: $(GIT_SUBMODULES)"
 ifneq ($(GIT_SUBMODULES),)
 	$(Q)cd $(TOP) && git submodule sync $(GIT_SUBMODULES)
-	$(Q)cd $(TOP) && git submodule update --init $(GIT_SUBMODULES)
+	# If available, do blobless partial clones of submodules to save time and space.
+	# A blobless partial clone lazily fetches data as needed, but has all the metadata available (tags, etc.).
+	# Fallback to standard submodule update if blobless isn't available (earlier than 2.36.0)
+	$(Q)cd $(TOP) && git submodule update --init $(GIT_SUBMODULES) --filter=blob:none || \
+	  git submodule update --init $(GIT_SUBMODULES)	               
 endif
 .PHONY: submodules