From 6a2f1279fd6588f83104b510448c23808a81e03b Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Wed, 14 Oct 2020 23:38:00 -0700
Subject: [PATCH] GBA: Clear GBP connection on reset

---
 CHANGES       | 1 +
 src/gba/gba.c | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/CHANGES b/CHANGES
index 1ccf0dab2..7fe5ce5af 100644
--- a/CHANGES
+++ b/CHANGES
@@ -22,6 +22,7 @@ Emulation fixes:
  - GB MBC: Fix some MBC3 bit masking
  - GB Video: Fix state after skipping BIOS (fixes mgba.io/i/1715 and mgba.io/i/1716)
  - GBA: Fix timing advancing too quickly in rare cases
+ - GBA: Clear GBP connection on reset
  - GBA Audio: Fix deserializing SOUNDCNT_L
  - GBA Audio: Fix stereo in XQ audio
  - GBA Audio: Fix volume/mute in XQ audio (fixes mgba.io/i/1864)
diff --git a/src/gba/gba.c b/src/gba/gba.c
index d47dcd8ef..23801dd43 100644
--- a/src/gba/gba.c
+++ b/src/gba/gba.c
@@ -216,6 +216,12 @@ void GBAReset(struct ARMCore* cpu) {
 
 	GBASIOReset(&gba->sio);
 
+	// GB Player SIO control should not be engaged before detection, even if we already know it's GBP
+	gba->memory.hw.devices &= ~HW_GB_PLAYER;
+	if (gba->sio.drivers.normal == &gba->memory.hw.gbpDriver.d) {
+		GBASIOSetDriver(&gba->sio, NULL, SIO_NORMAL_32);
+	}
+
 	bool isELF = false;
 #ifdef USE_ELF
 	struct ELF* elf = ELFOpen(gba->romVf);