From b7fce4207fc8b3a95d83ea846a3caf6e513f26a0 Mon Sep 17 00:00:00 2001
From: Cristian Maglie <c.maglie@bug.st>
Date: Tue, 21 Aug 2012 12:50:12 +0200
Subject: [PATCH] Fixed USB-CDC buffering. Now serial output performs much
 better.

---
 .../arduino/sam/cores/arduino/USB/CDC.cpp     |   1 -
 .../arduino/sam/cores/arduino/USB/USBCore.cpp |   6 ++++++
 .../sam/system/libsam/source/uotghs_device.c  |   2 +-
 .../arduino_due_x/libsam_sam3x8e_gcc_rel.a    | Bin 86052 -> 86056 bytes
 4 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/hardware/arduino/sam/cores/arduino/USB/CDC.cpp b/hardware/arduino/sam/cores/arduino/USB/CDC.cpp
index 64271b1f8..3c4f9feaf 100644
--- a/hardware/arduino/sam/cores/arduino/USB/CDC.cpp
+++ b/hardware/arduino/sam/cores/arduino/USB/CDC.cpp
@@ -228,7 +228,6 @@ size_t Serial_::write(uint8_t c)
 
 		if (r > 0)
 		{
-			USBD_Flush(CDC_TX);
 			return r;
 		} else
 		{
diff --git a/hardware/arduino/sam/cores/arduino/USB/USBCore.cpp b/hardware/arduino/sam/cores/arduino/USB/USBCore.cpp
index 3b4a2ced4..61113c20b 100644
--- a/hardware/arduino/sam/cores/arduino/USB/USBCore.cpp
+++ b/hardware/arduino/sam/cores/arduino/USB/USBCore.cpp
@@ -397,6 +397,12 @@ static void USB_ISR(void)
 
 		udd_ack_fifocon(CDC_RX);
 	}
+
+	if (Is_udd_sof())
+	{
+		udd_ack_sof();
+		USBD_Flush(CDC_TX);
+	}
 #endif
 
 	// EP 0 Interrupt
diff --git a/hardware/arduino/sam/system/libsam/source/uotghs_device.c b/hardware/arduino/sam/system/libsam/source/uotghs_device.c
index 23e815ccb..dff259658 100644
--- a/hardware/arduino/sam/system/libsam/source/uotghs_device.c
+++ b/hardware/arduino/sam/system/libsam/source/uotghs_device.c
@@ -115,7 +115,7 @@ void UDD_Attach(void)
 
 	// Enable USB line events
 	udd_enable_reset_interrupt();
-	//udd_enable_sof_interrupt();
+	udd_enable_sof_interrupt();
 
 	cpu_irq_restore(flags);
 }
diff --git a/hardware/arduino/sam/variants/arduino_due_x/libsam_sam3x8e_gcc_rel.a b/hardware/arduino/sam/variants/arduino_due_x/libsam_sam3x8e_gcc_rel.a
index a25e77ed9f1b5ddfa3ff8476b525b03973455b54..8488d4ee5e60c4cffafb4b6aaf6a382661762bf9 100644
GIT binary patch
delta 1070
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