diff --git a/src/modules/px4iofirmware/i2c.c b/src/modules/px4iofirmware/i2c.c
index 10aeb5c9fa..79b6546b39 100644
--- a/src/modules/px4iofirmware/i2c.c
+++ b/src/modules/px4iofirmware/i2c.c
@@ -149,12 +149,6 @@ interface_init(void)
 #endif
 }
 
-void
-interface_tick()
-{
-}
-
-
 /*
   reset the I2C bus
   used to recover from lockups
diff --git a/src/modules/px4iofirmware/px4io.c b/src/modules/px4iofirmware/px4io.c
index e70b3fe880..e28106971a 100644
--- a/src/modules/px4iofirmware/px4io.c
+++ b/src/modules/px4iofirmware/px4io.c
@@ -159,9 +159,6 @@ user_start(int argc, char *argv[])
 	/* start the FMU interface */
 	interface_init();
 
-	/* add a performance counter for the interface */
-	perf_counter_t interface_perf = perf_alloc(PC_ELAPSED, "interface");
-
 	/* add a performance counter for mixing */
 	perf_counter_t mixer_perf = perf_alloc(PC_ELAPSED, "mix");
 
@@ -203,11 +200,6 @@ user_start(int argc, char *argv[])
 		/* track the rate at which the loop is running */
 		perf_count(loop_perf);
 
-		/* kick the interface */
-		perf_begin(interface_perf);
-		interface_tick();
-		perf_end(interface_perf);
-
 		/* kick the mixer */
 		perf_begin(mixer_perf);
 		mixer_tick();
@@ -218,6 +210,7 @@ user_start(int argc, char *argv[])
 		controls_tick();
 		perf_end(controls_perf);
 
+#if 0
 		/* check for debug activity */
 		show_debug_messages();
 
@@ -234,6 +227,7 @@ user_start(int argc, char *argv[])
 				  (unsigned)minfo.mxordblk);
 			last_debug_time = hrt_absolute_time();
 		}
+#endif
 	}
 }
 
diff --git a/src/modules/px4iofirmware/serial.c b/src/modules/px4iofirmware/serial.c
index 94d7407dff..e9adc8cd69 100644
--- a/src/modules/px4iofirmware/serial.c
+++ b/src/modules/px4iofirmware/serial.c
@@ -74,9 +74,6 @@ static DMA_HANDLE	rx_dma;
 static int		serial_interrupt(int irq, void *context);
 static void		dma_reset(void);
 
-/* if we spend this many ticks idle, reset the DMA */
-static unsigned		idle_ticks;
-
 static struct IOPacket	dma_packet;
 
 /* serial register accessors */
@@ -150,16 +147,6 @@ interface_init(void)
 	debug("serial init");
 }
 
-void
-interface_tick()
-{
-	/* XXX look for stuck/damaged DMA and reset? */
-	if (idle_ticks++ > 100) {
-		dma_reset();
-		idle_ticks = 0;
-	}
-}
-
 static void
 rx_handle_packet(void)
 {
@@ -230,9 +217,6 @@ rx_dma_callback(DMA_HANDLE handle, uint8_t status, void *arg)
 	/* disable UART DMA */
 	rCR3 &= ~(USART_CR3_DMAT | USART_CR3_DMAR);
 
-	/* reset the idle counter */
-	idle_ticks = 0;
-
 	/* handle the received packet */
 	rx_handle_packet();
 
@@ -308,6 +292,7 @@ serial_interrupt(int irq, void *context)
 
 			/* it was too short - possibly truncated */
 			perf_count(pc_badidle);
+			dma_reset();
 			return 0;
 		}
 
@@ -343,7 +328,8 @@ dma_reset(void)
 		sizeof(dma_packet),
 		DMA_CCR_MINC		|
 		DMA_CCR_PSIZE_8BITS	|
-		DMA_CCR_MSIZE_8BITS);
+		DMA_CCR_MSIZE_8BITS     |
+		DMA_CCR_PRIVERYHI);
 
 	/* start receive DMA ready for the next packet */
 	stm32_dmastart(rx_dma, rx_dma_callback, NULL, false);