Disable 20MB/s support until data corruption issue is fixed.

lib/SCSI2SD/CHANGELOG

@@ -1,4 +1,5 @@
-2016XXXX		6.0.7
+20160827		6.0.8
+	- Fixed "protocol error" issues when saving configuration to SD cards.
 	- Synchronous transfers supported ! 5MB/s and 10MB/s supported.
 	- Fix for accessing data via USB with more than 2 devices configured.
 

lib/SCSI2SD/src/firmware/config.c

@@ -37,7 +37,7 @@
 
 #include <string.h>
 
-static const uint16_t FIRMWARE_VERSION = 0x0607;
+static const uint16_t FIRMWARE_VERSION = 0x0608;
 
 // 1 flash row
 static const uint8_t DEFAULT_CONFIG[128] =

lib/SCSI2SD/src/firmware/scsi.c

@@ -766,11 +766,17 @@ static void process_MessageOut()
 				scsiDev.target->syncPeriod = 0;
 			} else {
 				scsiDev.target->syncOffset = offset < 15 ? offset : 15;
+				// FAST20 / 50ns / 20MHz is disabled for now due to
+				// data corruption while reading data. We can count the
+				// ACK's correctly, but can't save the data to a register
+				// before it changes.
+				// TODO work out the fastest sync period that will work
+				/*
 				if (transferPeriod <= 12)
 				{
 					scsiDev.target->syncPeriod = 12; // 50ns, 20MB/s
 				}
-				else if (transferPeriod <= 25)
+				else */if (transferPeriod <= 25)
 				{
 					scsiDev.target->syncPeriod = 25; // 100ns, 10MB/s
 				} else {