diff --git a/arch/arm/src/stm32f7/Kconfig b/arch/arm/src/stm32f7/Kconfig
index 95e931abc2..123277ba13 100644
--- a/arch/arm/src/stm32f7/Kconfig
+++ b/arch/arm/src/stm32f7/Kconfig
@@ -1614,6 +1614,18 @@ config UART8_RXDMA
 	---help---
 		In high data rate usage, Rx DMA may eliminate Rx overrun errors
 
+config STM32F7_SERIAL_RXDMA_BUFFER_SIZE
+	int "Rx DMA buffer size"
+	default 32
+	depends on USART1_RXDMA || USART2_RXDMA || USART3_RXDMA || UART4_RXDMA || UART5_RXDMA || USART6_RXDMA || UART7_RXDMA || UART8_RXDMA
+	---help---
+		The DMA buffer size when using RX DMA to emulate a FIFO.
+
+		When streaming data, the generic serial layer will be called
+		every time the FIFO receives half this number of bytes.
+
+		Value given here will be rounded up to next multiple of 32 bytes.
+
 config SERIAL_DISABLE_REORDERING
 	bool "Disable reordering of ttySx devices."
 	depends on STM32F7_USART1 || STM32F7_USART2 || STM32F7_USART3 || STM32F7_UART4 || STM32F7_UART5 || STM32F7_USART6 || STM32F7_UART7 || STM32F7_UART8
diff --git a/arch/arm/src/stm32f7/stm32_serial.c b/arch/arm/src/stm32f7/stm32_serial.c
index 5c2b8b74bc..ce6e7db9a7 100644
--- a/arch/arm/src/stm32f7/stm32_serial.c
+++ b/arch/arm/src/stm32f7/stm32_serial.c
@@ -159,15 +159,30 @@
 
 /* The DMA buffer size when using RX DMA to emulate a FIFO.
  *
- * When streaming data, the generic serial layer will be called
- * every time the FIFO receives half this number of bytes.
+ * When streaming data, the generic serial layer will be called every time
+ * the FIFO receives half this number of bytes.
  *
- * This buffer size should be an even multiple of the Cortex-M7
- * D-Cache line size so that it can be individually invalidated.
+ * This buffer size should be an even multiple of the Cortex-M7 D-Cache line
+ * size, ARMV7M_DCACHE_LINESIZE, so that it can be individually invalidated.
+ *
+ * Should there be a Cortex-M7 without a D-Cache, ARMV7M_DCACHE_LINESIZE
+ * would be zero!
  */
 
+#  if !defined(ARMV7M_DCACHE_LINESIZE) || ARMV7M_DCACHE_LINESIZE == 0
+#    undef ARMV7M_DCACHE_LINESIZE
+#    define ARMV7M_DCACHE_LINESIZE 32
+#  endif
+
+#  if !defined(CONFIG_STM32F7_SERIAL_RXDMA_BUFFER_SIZE) || \
+      (CONFIG_STM32F7_SERIAL_RXDMA_BUFFER_SIZE < ARMV7M_DCACHE_LINESIZE)
+#    undef CONFIG_STM32F7_SERIAL_RXDMA_BUFFER_SIZE
+#    define CONFIG_STM32F7_SERIAL_RXDMA_BUFFER_SIZE ARMV7M_DCACHE_LINESIZE
+#  endif
+
 #  define RXDMA_BUFFER_MASK   (ARMV7M_DCACHE_LINESIZE - 1)
-#  define RXDMA_BUFFER_SIZE   ((32 + RXDMA_BUFFER_MASK) & ~RXDMA_BUFFER_MASK)
+#  define RXDMA_BUFFER_SIZE   ((CONFIG_STM32F7_SERIAL_RXDMA_BUFFER_SIZE \
+                                + RXDMA_BUFFER_MASK) & ~RXDMA_BUFFER_MASK)
 
 /* DMA priority */