From 3333f1b6ab84234f51aa901ec29cdc6d7f0998c5 Mon Sep 17 00:00:00 2001 From: Timothy Pearson Date: Thu, 4 Jun 2015 00:10:03 -0500 Subject: [PATCH 043/143] amd/amdmct/mct_ddr3: Improve SPD DIMM detect reliability Change-Id: Ifab63eca2233c63a6a42ab8b7e742f8e47fb2a09 Signed-off-by: Timothy Pearson --- 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 5344ff9..e60adb7 100644 --- a/src/northbridge/amd/amdmct/mct_ddr3/mct_d.c +++ b/src/northbridge/amd/amdmct/mct_ddr3/mct_d.c @@ -3657,6 +3657,7 @@ 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); @@ -3677,10 +3678,20 @@ 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'*/ -- 1.7.9.5