diff --git a/nuttx-configs/auav-x21/include/board.h b/nuttx-configs/auav-x21/include/board.h
index 7d80dda9ba..f5205f3b5d 100755
--- a/nuttx-configs/auav-x21/include/board.h
+++ b/nuttx-configs/auav-x21/include/board.h
@@ -171,29 +171,29 @@
  * to service FIFOs in interrupt driven mode.  These values have not been
  * tuned!!!
  *
- * HCLK=72MHz, SDIOCLK=72MHz, SDIO_CK=HCLK/(178+2)=400 KHz
+ * SDIOCLK=48MHz, SDIO_CK=SDIOCLK/(118+2)=400 KHz
  */
 
-#define SDIO_INIT_CLKDIV        (178 << SDIO_CLKCR_CLKDIV_SHIFT)
+#define SDIO_INIT_CLKDIV        (118 << SDIO_CLKCR_CLKDIV_SHIFT)
 
-/* DMA ON:  HCLK=72 MHz, SDIOCLK=72MHz, SDIO_CK=HCLK/(2+2)=18 MHz
- * DMA OFF: HCLK=72 MHz, SDIOCLK=72MHz, SDIO_CK=HCLK/(3+2)=14.4 MHz
+/* DMA ON:  SDIOCLK=48MHz, SDIO_CK=SDIOCLK/(1+2)=16 MHz
+ * DMA OFF: SDIOCLK=48MHz, SDIO_CK=SDIOCLK/(2+2)=12 MHz
  */
 
 #ifdef CONFIG_SDIO_DMA
-#  define SDIO_MMCXFR_CLKDIV    (2 << SDIO_CLKCR_CLKDIV_SHIFT)
+#  define SDIO_MMCXFR_CLKDIV    (1 << SDIO_CLKCR_CLKDIV_SHIFT)
 #else
-#  define SDIO_MMCXFR_CLKDIV    (3 << SDIO_CLKCR_CLKDIV_SHIFT)
+#  define SDIO_MMCXFR_CLKDIV    (2 << SDIO_CLKCR_CLKDIV_SHIFT)
 #endif
 
-/* DMA ON:  HCLK=72 MHz, SDIOCLK=72MHz, SDIO_CK=HCLK/(1+2)=24 MHz
- * DMA OFF: HCLK=72 MHz, SDIOCLK=72MHz, SDIO_CK=HCLK/(3+2)=14.4 MHz
+/* DMA ON:  SDIOCLK=48MHz, SDIO_CK=SDIOCLK/(1+2)=16 MHz
+ * DMA OFF: SDIOCLK=48MHz, SDIO_CK=SDIOCLK/(2+2)=12 MHz
  */
 
 #ifdef CONFIG_SDIO_DMA
 #  define SDIO_SDXFR_CLKDIV     (1 << SDIO_CLKCR_CLKDIV_SHIFT)
 #else
-#  define SDIO_SDXFR_CLKDIV     (3 << SDIO_CLKCR_CLKDIV_SHIFT)
+#  define SDIO_SDXFR_CLKDIV     (2 << SDIO_CLKCR_CLKDIV_SHIFT)
 #endif
 
 /* DMA Channl/Stream Selections *****************************************************/