From 5a30d9f5a0db0b51f4275c3207580e1e8c83fa34 Mon Sep 17 00:00:00 2001
From: Steve Evans <Steve@SCEvans.com>
Date: Sun, 26 Jun 2022 22:31:00 +0100
Subject: [PATCH] Only write to FLASH once 64 bytes are buffered

---
 src/main/blackbox/blackbox_io.c | 6 +++---
 src/main/io/flashfs.c           | 9 ++++++---
 src/main/io/flashfs.h           | 2 +-
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/main/blackbox/blackbox_io.c b/src/main/blackbox/blackbox_io.c
index 7db5301dd8..f966a0f2f5 100644
--- a/src/main/blackbox/blackbox_io.c
+++ b/src/main/blackbox/blackbox_io.c
@@ -214,7 +214,7 @@ void blackboxDeviceFlush(void)
          * devices will progressively write in the background without Blackbox calling anything.
          */
     case BLACKBOX_DEVICE_FLASH:
-        flashfsFlushAsync();
+        flashfsFlushAsync(false);
         break;
 #endif // USE_FLASHFS
 
@@ -237,7 +237,7 @@ bool blackboxDeviceFlushForce(void)
 
 #ifdef USE_FLASHFS
     case BLACKBOX_DEVICE_FLASH:
-        return flashfsFlushAsync();
+        return flashfsFlushAsync(true);
 #endif // USE_FLASHFS
 
 #ifdef USE_SDCARD
@@ -735,7 +735,7 @@ blackboxBufferReserveStatus_e blackboxDeviceReserveBufferSpace(int32_t bytes)
              * that the Blackbox header writing code doesn't have to guess about the best time to ask flashfs to
              * flush, and doesn't stall waiting for a flush that would otherwise not automatically be called.
              */
-            flashfsFlushAsync();
+            flashfsFlushAsync(true);
         }
         return BLACKBOX_RESERVE_TEMPORARY_FAILURE;
 #endif // USE_FLASHFS
diff --git a/src/main/io/flashfs.c b/src/main/io/flashfs.c
index 0e02edd45e..8e8c16bd57 100644
--- a/src/main/io/flashfs.c
+++ b/src/main/io/flashfs.c
@@ -38,6 +38,7 @@
 
 #include "platform.h"
 
+#include "build/debug.h"
 #include "common/printf.h"
 #include "drivers/flash.h"
 
@@ -343,7 +344,7 @@ uint32_t flashfsGetOffset(void)
  * Returns true if all data in the buffer has been flushed to the device, or false if
  * there is still data to be written (call flush again later).
  */
-bool flashfsFlushAsync(void)
+bool flashfsFlushAsync(bool force)
 {
     uint8_t const * buffers[2];
     uint32_t bufferSizes[2];
@@ -373,7 +374,9 @@ bool flashfsFlushAsync(void)
 #endif
 
     bufCount = flashfsGetDirtyDataBuffers(buffers, bufferSizes);
-    if (bufCount) {
+    uint32_t bufferedBytes = bufferSizes[0] + bufferSizes[1];
+
+    if (bufCount && (force || (bufferedBytes >= FLASHFS_WRITE_BUFFER_AUTO_FLUSH_LEN))) {
         flashfsWriteBuffers(buffers, bufferSizes, bufCount, false);
     }
 
@@ -427,7 +430,7 @@ void flashfsWriteByte(uint8_t byte)
     }
 
     if (flashfsTransmitBufferUsed() >= FLASHFS_WRITE_BUFFER_AUTO_FLUSH_LEN) {
-        flashfsFlushAsync();
+        flashfsFlushAsync(false);
     }
 }
 
diff --git a/src/main/io/flashfs.h b/src/main/io/flashfs.h
index c131326ee4..0817d26b05 100644
--- a/src/main/io/flashfs.h
+++ b/src/main/io/flashfs.h
@@ -44,7 +44,7 @@ void flashfsWrite(const uint8_t *data, unsigned int len, bool sync);
 
 int flashfsReadAbs(uint32_t offset, uint8_t *data, unsigned int len);
 
-bool flashfsFlushAsync(void);
+bool flashfsFlushAsync(bool force);
 void flashfsFlushSync(void);
 
 void flashfsClose(void);