[coreboot-gerrit] Patch set updated for coreboot: amd/amdmct/mct_ddr3: Improve SPD DIMM detect reliability

[Timothy Pearson (tpearson@raptorengineeringinc.com)]

Timothy Pearson (tpearson at raptorengineeringinc.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/11975

-gerrit

commit 5d040f503b8d7a159a5ca7a7a581f950ecdb33c5
Author: Timothy Pearson <tpearson at raptorengineeringinc.com>
Date:   Thu Jun 4 00:10:03 2015 -0500

    amd/amdmct/mct_ddr3: Improve SPD DIMM detect reliability
    
    Change-Id: Ifab63eca2233c63a6a42ab8b7e742f8e47fb2a09
    Signed-off-by: Timothy Pearson <tpearson at raptorengineeringinc.com>
---
 src/northbridge/amd/amdmct/mct_ddr3/mct_d.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/northbridge/amd/amdmct/mct_ddr3/mct_d.c b/src/northbridge/amd/amdmct/mct_ddr3/mct_d.c
index b79b6c9..771d743 100644
--- a/src/northbridge/amd/amdmct/mct_ddr3/mct_d.c
+++ b/src/northbridge/amd/amdmct/mct_ddr3/mct_d.c
@@ -3654,6 +3654,7 @@ static u8 DIMMPresence_D(struct MCTStatStruc *pMCTstat,
 	u8 devwidth;
 	u16 DimmSlots;
 	u8 byte = 0, bytex;
+	uint8_t crc_status;
 
 	/* preload data structure with addrs */
 	mctGet_DIMMAddr(pDCTstat, pDCTstat->Node_ID);
@@ -3674,10 +3675,20 @@ static u8 DIMMPresence_D(struct MCTStatStruc *pMCTstat,
 			int status;
 			smbaddr = Get_DIMMAddress_D(pDCTstat, i);
 			status = mctRead_SPD(smbaddr, SPD_ByteUse);
+			if (status >= 0) {
+				/* Verify result */
+				status = mctRead_SPD(smbaddr, SPD_ByteUse);
+			}
 			if (status >= 0) { /* SPD access is ok */
 				pDCTstat->DIMMPresent |= 1 << i;
 				read_spd_bytes(pMCTstat, pDCTstat, i);
-				if (crcCheck(pDCTstat, i)) { /* CRC is OK */
+				crc_status = crcCheck(pDCTstat, i);
+				if (!crc_status) {
+					/* Try again in case there was a transient glitch */
+					read_spd_bytes(pMCTstat, pDCTstat, i);
+					crc_status = crcCheck(pDCTstat, i);
+				}
+				if (crc_status) { /* CRC is OK */
 					byte = pDCTstat->spd_data.spd_bytes[i][SPD_TYPE];
 					if (byte == JED_DDR3SDRAM) {
 						/*Dimm is 'Present'*/