Index: sys/dev/sdhci/sdhci.h
===================================================================
--- sys/dev/sdhci/sdhci.h
+++ sys/dev/sdhci/sdhci.h
@@ -32,8 +32,8 @@
 
 #include "opt_mmccam.h"
 
-#define	DMA_BLOCK_SIZE	4096
-#define	DMA_BOUNDARY	0	/* DMA reload every 4K */
+#define	DMA_BLOCK_SIZE	512*1024
+#define	DMA_BOUNDARY	7	/* DMA reload every 512K */
 
 /* Controller doesn't honor resets unless we touch the clock register */
 #define	SDHCI_QUIRK_CLOCK_BEFORE_RESET			(1 << 0)