M CHANGES → CHANGES

@@ -22,6 +22,7 @@ - GB MBC: Fix MBC1 mode changing behavior
  - 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)

M src/gba/gba.c → src/gba/gba.c

@@ -216,6 +216,12 @@ GBATimerInit(gba);
 
 	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);