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[U-Boot] fsl/deepsleep: avoid the DDR restore from being optimized out

Message ID 1429499816-30238-1-git-send-email-Yuantian.Tang@freescale.com
State Accepted
Delegated to: York Sun
Headers show

Commit Message

tang yuantian April 20, 2015, 3:16 a.m. UTC 
From: Tang Yuantian <Yuantian.Tang@freescale.com>

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>
---
 board/freescale/common/mpc85xx_sleep.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

York Sun May 5, 2015, 4:36 p.m. UTC | #1 
On 04/19/2015 08:16 PM, Yuantian.Tang@freescale.com wrote:
> From: Tang Yuantian <Yuantian.Tang@freescale.com>
> 
> 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>
> ---

Applied to u-boot-mpc85xx master. Awaiting upstream.

York
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Patch

diff --git a/board/freescale/common/mpc85xx_sleep.c b/board/freescale/common/mpc85xx_sleep.c
index 9e4132c..e9cbd51 100644
--- a/board/freescale/common/mpc85xx_sleep.c
+++ b/board/freescale/common/mpc85xx_sleep.c
@@ -43,16 +43,16 @@  void fsl_dp_disable_console(void)
  */
 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();
 }