From 7e624c6857deaa8876ca02dbca195cd2c3f0f36d Mon Sep 17 00:00:00 2001
From: Vicki Pfau <vi@endrift.com>
Date: Fri, 3 Feb 2023 02:08:14 -0800
Subject: [PATCH] GBA SIO: Normal mode transfers with no clock should not
 finish (fixes #2811)

---
 CHANGES                | 1 +
 src/gba/sio/lockstep.c | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/CHANGES b/CHANGES
index 925623fc8..75c23d765 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,7 @@ Emulation fixes:
  - GBA Memory: Make VRAM access stalls only apply to BG RAM
  - GBA SIO: Fix SIOCNT SI pin value after attaching player 2 (fixes mgba.io/i/2805)
  - GBA SIO: Fix unconnected normal mode SIOCNT SI bit (fixes mgba.io/i/2810)
+ - GBA SIO: Normal mode transfers with no clock should not finish (fixes mgba.io/i/2811)
  - GBA Timers: Cascading timers don't tick when disabled (fixes mgba.io/i/2812)
 Other fixes:
  - Core: Allow sending thread requests to a crashed core (fixes mgba.io/i/2784)
diff --git a/src/gba/sio/lockstep.c b/src/gba/sio/lockstep.c
index db92c50a5..3ea1b5cc9 100644
--- a/src/gba/sio/lockstep.c
+++ b/src/gba/sio/lockstep.c
@@ -532,7 +532,7 @@ static uint16_t GBASIOLockstepNodeNormalWriteRegister(struct GBASIODriver* drive
 				}
 			}
 		}
-		if (value & 0x0080) {
+		if ((value & 0x0081) == 0x0081) {
 			if (!node->id) {
 				// Frequency
 				int32_t cycles;
@@ -559,7 +559,7 @@ static uint16_t GBASIOLockstepNodeNormalWriteRegister(struct GBASIODriver* drive
 					value &= ~0x0080;
 				}
 			} else {
-
+				// TODO
 			}
 		}
 	} else if (address == REG_SIODATA32_LO) {