diff --git a/scripts/gdb.py b/scripts/gdb.py
index eb28ed88..286627c2 100644
--- a/scripts/gdb.py
+++ b/scripts/gdb.py
@@ -241,7 +241,7 @@ class Target:
 			block = 0
 			for i in range(len(self.blocks)):
 				block += 1
-				if callable(progress_cb):
+				if callable(progress_cb) and totalblocks > 0:
 					progress_cb(block*100/totalblocks)
 
 				# Erase the block
diff --git a/src/gdb_main.c b/src/gdb_main.c
index 1a5805af..ed1f2fe0 100644
--- a/src/gdb_main.c
+++ b/src/gdb_main.c
@@ -155,7 +155,7 @@ int gdb_main_loop(struct target_controller *tc, bool in_syscall)
 			}
 		case 's':	/* 's [addr]': Single step [start at addr] */
 			single_step = true;
-			// Fall through to resume target
+			/* fall through */
 		case 'c':	/* 'c [addr]': Continue [at addr] */
 			if(!cur_target) {
 				gdb_putpacketz("X1D");
@@ -165,7 +165,7 @@ int gdb_main_loop(struct target_controller *tc, bool in_syscall)
 			target_halt_resume(cur_target, single_step);
 			SET_RUN_STATE(1);
 			single_step = false;
-			// Fall through to wait for target halt
+			/* fall through */
 		case '?': {	/* '?': Request reason for target halt */
 			/* This packet isn't documented as being mandatory,
 			 * but GDB doesn't work without it. */
@@ -482,4 +482,3 @@ void gdb_main(void)
 {
 	gdb_main_loop(&gdb_controller, false);
 }
-
diff --git a/src/platforms/common/cdcacm.c b/src/platforms/common/cdcacm.c
index 127a2c56..a6931ee2 100644
--- a/src/platforms/common/cdcacm.c
+++ b/src/platforms/common/cdcacm.c
@@ -449,6 +449,7 @@ static int cdcacm_control_request(usbd_device *dev,
 		switch(req->wIndex) {
 		case 2:
 			usbuart_set_line_coding((struct usb_cdc_line_coding*)*buf);
+			return 1;
 		case 0:
 			return 1; /* Ignore on GDB Port */
 		default:
@@ -466,6 +467,7 @@ static int cdcacm_control_request(usbd_device *dev,
 
 			return 1;
 		}
+		return 0;
 	case DFU_DETACH:
 		if(req->wIndex == DFU_IF_NO) {
 			*complete = dfu_detach_complete;
@@ -566,4 +568,3 @@ void USB_ISR(void)
 {
 	usbd_poll(usbdev);
 }
-
diff --git a/src/platforms/stm32/usbuart.c b/src/platforms/stm32/usbuart.c
index 0d1772a3..a466ab55 100644
--- a/src/platforms/stm32/usbuart.c
+++ b/src/platforms/stm32/usbuart.c
@@ -217,7 +217,7 @@ void USBUSART_ISR(void)
 {
 	uint32_t err = USART_SR(USBUSART);
 	char c = usart_recv(USBUSART);
-	if (err & (USART_SR_ORE | USART_SR_FE))
+	if (err & (USART_SR_ORE | USART_SR_FE | USART_SR_NE))
 		return;
 
 	/* Turn on LED */
diff --git a/src/target/cortexm.c b/src/target/cortexm.c
index 4e941060..abd64f4a 100644
--- a/src/target/cortexm.c
+++ b/src/target/cortexm.c
@@ -78,6 +78,9 @@ struct cortexm_priv {
 	unsigned hw_breakpoint_max;
 	/* Copy of DEMCR for vector-catch */
 	uint32_t demcr;
+	/* Cache parameters */
+	bool has_cache;
+	uint32_t dcache_minline;
 };
 
 /* Register number tables */
@@ -179,13 +182,40 @@ ADIv5_AP_t *cortexm_ap(target *t)
 	return ((struct cortexm_priv *)t->priv)->ap;
 }
 
+static void cortexm_cache_clean(target *t, target_addr addr, size_t len, bool invalidate)
+{
+	struct cortexm_priv *priv = t->priv;
+	if (!priv->has_cache || (priv->dcache_minline == 0))
+		return;
+	uint32_t cache_reg = invalidate ? CORTEXM_DCCIMVAC : CORTEXM_DCCMVAC;
+	size_t minline = priv->dcache_minline;
+
+	/* flush data cache for RAM regions that intersect requested region */
+	target_addr mem_end = addr + len; /* following code is NOP if wraparound */
+	/* requested region is [src, src_end) */
+	for (struct target_ram *r = t->ram; r; r = r->next) {
+		target_addr ram = r->start;
+		target_addr ram_end = r->start + r->length;
+		/* RAM region is [ram, ram_end) */
+		if (addr > ram)
+			ram = addr;
+		if (mem_end < ram_end)
+			ram_end = mem_end;
+		/* intersection is [ram, ram_end) */
+		for (ram &= ~(minline-1); ram < ram_end; ram += minline)
+			adiv5_mem_write(cortexm_ap(t), cache_reg, &ram, 4);
+	}
+}
+
 static void cortexm_mem_read(target *t, void *dest, target_addr src, size_t len)
 {
+	cortexm_cache_clean(t, src, len, false);
 	adiv5_mem_read(cortexm_ap(t), dest, src, len);
 }
 
 static void cortexm_mem_write(target *t, target_addr dest, const void *src, size_t len)
 {
+	cortexm_cache_clean(t, dest, len, true);
 	adiv5_mem_write(cortexm_ap(t), dest, src, len);
 }
 
@@ -251,6 +281,15 @@ bool cortexm_probe(ADIv5_AP_t *ap)
 	priv->demcr = CORTEXM_DEMCR_TRCENA | CORTEXM_DEMCR_VC_HARDERR |
 			CORTEXM_DEMCR_VC_CORERESET;
 
+	/* Check cache type */
+	uint32_t ctr = target_mem_read32(t, CORTEXM_CTR);
+	if ((ctr >> 29) == 4) {
+		priv->has_cache = true;
+		priv->dcache_minline = 4 << (ctr & 0xf);
+	} else {
+		target_check_error(t);
+	}
+
 #define PROBE(x) \
 	do { if ((x)(t)) return true; else target_check_error(t); } while (0)
 
@@ -551,6 +590,9 @@ void cortexm_halt_resume(target *t, bool step)
 			cortexm_pc_write(t, pc + 2);
 	}
 
+	if (priv->has_cache)
+		target_mem_write32(t, CORTEXM_ICIALLU, 0);
+
 	target_mem_write32(t, CORTEXM_DHCSR, dhcsr);
 }
 
diff --git a/src/target/cortexm.h b/src/target/cortexm.h
index bf1d821d..e9bf5476 100644
--- a/src/target/cortexm.h
+++ b/src/target/cortexm.h
@@ -37,6 +37,17 @@
 #define CORTEXM_DCRDR		(CORTEXM_SCS_BASE + 0xDF8)
 #define CORTEXM_DEMCR		(CORTEXM_SCS_BASE + 0xDFC)
 
+/* Cache identification */
+#define CORTEXM_CLIDR		(CORTEXM_SCS_BASE + 0xD78)
+#define CORTEXM_CTR		(CORTEXM_SCS_BASE + 0xD7C)
+#define CORTEXM_CCSIDR		(CORTEXM_SCS_BASE + 0xD80)
+#define CORTEXM_CSSELR		(CORTEXM_SCS_BASE + 0xD84)
+
+/* Cache maintenance operations */
+#define CORTEXM_ICIALLU		(CORTEXM_SCS_BASE + 0xF50)
+#define CORTEXM_DCCMVAC		(CORTEXM_SCS_BASE + 0xF68)
+#define CORTEXM_DCCIMVAC	(CORTEXM_SCS_BASE + 0xF70)
+
 #define CORTEXM_FPB_BASE	(CORTEXM_PPB_BASE + 0x2000)
 
 /* ARM Literature uses FP_*, we use CORTEXM_FPB_* consistently */
diff --git a/src/target/stm32f1.c b/src/target/stm32f1.c
index c9823db3..4064e01a 100644
--- a/src/target/stm32f1.c
+++ b/src/target/stm32f1.c
@@ -136,11 +136,13 @@ bool stm32f1_probe(target *t)
 		stm32f1_add_flash(t, 0x8000000, 0x80000, 0x800);
 		target_add_commands(t, stm32f1_cmd_list, "STM32 HD/CL");
 		return true;
-	case 0x422:  /* STM32F30x */
-	case 0x432:  /* STM32F37x */
 	case 0x438:  /* STM32F303x6/8 and STM32F328 */
-	case 0x439:  /* STM32F302C8 */
+	case 0x422:  /* STM32F30x */
 	case 0x446:  /* STM32F303xD/E and STM32F398xE */
+		target_add_ram(t, 0x10000000, 0x4000);
+		/* fall through */
+	case 0x432:  /* STM32F37x */
+	case 0x439:  /* STM32F302C8 */
 		t->driver = "STM32F3";
 		target_add_ram(t, 0x20000000, 0x10000);
 		stm32f1_add_flash(t, 0x8000000, 0x80000, 0x800);