From 0c90b7d95c0f80fb675ae3799ecc19e56e6dd520 Mon Sep 17 00:00:00 2001
From: Armel FAUVEAU <armel.fauveau@globalis-ms.com>
Date: Wed, 25 Feb 2026 04:49:38 +0100
Subject: [PATCH] Fix freeze when using K5Viewer and USB-C

---
 App/driver/vcp.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/App/driver/vcp.c b/App/driver/vcp.c
index 2ef8ffe0..563c923c 100644
--- a/App/driver/vcp.c
+++ b/App/driver/vcp.c
@@ -80,14 +80,20 @@ bool VCP_ScreenshotPing(void)
     static ParseState_t state    = STATE_IDLE;
 
     bool     connected = false;
-    uint32_t write_ptr = VCP_RxBufPointer;
+    uint32_t write_ptr = VCP_RxBufPointer;  // snapshot once — ISR may update concurrently
 
-    while (read_ptr != write_ptr)
+    // Cap bytes processed per call to VCP_RX_BUF_SIZE.
+    // Prevents unbounded loop if the ISR write pointer laps read_ptr
+    // (buffer overflow / corrupted state), which would freeze the firmware.
+    uint32_t processed = 0;
+
+    while (read_ptr != write_ptr && processed < VCP_RX_BUF_SIZE)
     {
         uint8_t b = VCP_RxBuf[read_ptr];
         read_ptr++;
         if (read_ptr >= VCP_RX_BUF_SIZE)
             read_ptr = 0;
+        processed++;
 
         switch (state)
         {