fsl/deepsleep: avoid the DDR restore from being optimized out

Function dp_ddr_restore is to restore the first 128-byte space of DDR. However those codes may be optimized out by compiler since the destination address is at 0x0. In order to avoid compiler optimization, we restore the space from high address, which is not at 0x0, to low address. Signed-off-by: Tang Yuantian <Yuantian.Tang@freescale.com> Reviewed-by: York Sun <yorksun@freescale.com>

fsl/deepsleep: avoid the DDR restore from being optimized out
Function dp_ddr_restore is to restore the first 128-byte space of DDR. However those codes may be optimized out by compiler since the destination address is at 0x0. In order to avoid compiler optimization, we restore the space from high address, which is not at 0x0, to low address. Signed-off-by: Tang Yuantian <Yuantian.Tang@freescale.com> Reviewed-by: York Sun <yorksun@freescale.com>
Tang Yuantian · York Sun
1 parent 438031e1bc
Showing 1 changed file with 4 additions and 4 deletions Side-by-side Diff
board/freescale/common/mpc85xx_sleep.c
@@ -43,16 +43,16 @@
  */
 static void dp_ddr_restore(void)
 {
-	volatile u64 *src, *dst;
+	u64 *src, *dst;
 	int i;
 	struct ccsr_scfg __iomem *scfg = (void *)CONFIG_SYS_MPC85xx_SCFG;
  
 	/* get the address of ddr date from SPARECR3 */
-	src = (u64 *)in_be32(&scfg->sparecr[2]);
-	dst = (u64 *)CONFIG_SYS_SDRAM_BASE;
+	src = (u64 *)(in_be32(&scfg->sparecr[2]) + DDR_BUFF_LEN - 8);
+	dst = (u64 *)(CONFIG_SYS_SDRAM_BASE + DDR_BUFF_LEN - 8);
  
 	for (i = 0; i < DDR_BUFF_LEN / 8; i++)
-		*dst++ = *src++;
+		*dst-- = *src--;
  
 	flush_dcache();
 }
...	...	@@ -43,16 +43,16 @@
43	43	*/
44	44	static void dp_ddr_restore(void)
45	45	{
46		- volatile u64 src, dst;
	46	+ u64 src, dst;
47	47	int i;
48	48	struct ccsr_scfg __iomem scfg = (void )CONFIG_SYS_MPC85xx_SCFG;
49	49
50	50	/* get the address of ddr date from SPARECR3 */
51		- src = (u64 *)in_be32(&scfg->sparecr[2]);
52		- dst = (u64 *)CONFIG_SYS_SDRAM_BASE;
	51	+ src = (u64 *)(in_be32(&scfg->sparecr[2]) + DDR_BUFF_LEN - 8);
	52	+ dst = (u64 *)(CONFIG_SYS_SDRAM_BASE + DDR_BUFF_LEN - 8);
53	53
54	54	for (i = 0; i < DDR_BUFF_LEN / 8; i++)
55		- dst++ = src++;
	55	+ dst-- = src--;
56	56
57	57	flush_dcache();
58	58	}