From eba9c37027c7a913beaf0835b2233078ca7e8011 Mon Sep 17 00:00:00 2001
From: jgroman <jgroman@users.noreply.github.com>
Date: Fri, 2 Feb 2024 12:54:17 +0100
Subject: [PATCH] Fix SRAM loading on invalid flash

---
 src/gowin.cpp | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/gowin.cpp b/src/gowin.cpp
index 1f7cbc0..fef7724 100644
--- a/src/gowin.cpp
+++ b/src/gowin.cpp
@@ -883,8 +883,19 @@ void Gowin::sendClkUs(unsigned us)
 bool Gowin::eraseSRAM()
 {
 	printInfo("Erase SRAM ", false);
+	uint32_t status = readStatusReg();
 	if (_verbose)
-		displayReadReg("before erase sram", readStatusReg());
+		displayReadReg("before erase sram", status);
+
+	// If flash is invalid, send extra cmd 0x3F before SRAM erase
+	// This is required on GW5A-25
+	bool auto_boot_2nd_fail = (status & 0x8) >> 3;
+	if ((_idcode == 0x0001281B) && auto_boot_2nd_fail)
+	{
+		disableCfg();
+		send_command(0x3F);
+		send_command(NOOP);
+	}
 
 	if (!enableCfg()) {
 		printError("FAIL");