Improve DIMM detection for AMCC Yucca 440SPe board
Improved the memory DIMM detection for the Yucca 440SPe board for
the case where a memory DIMM is falsely detected as present.
This issue is seen on some AMCC Yucca 440SPe validation boards if
only one 512MB memory DIMM is installed, i.e. DIMM slot 0 is
populated and DIMM slot 1 is empty. In this case, U-Boot does
not correctly detect that there is only one DIMM memory module
installed and will falsely detect two DIMM memory modules are
present and therefore U-Boot will not calculate the correct amount
of total memory and u-boot will not booting up.
Patch by Adam Graham, 24 Aug 2006
diff --git a/board/amcc/yucca/yucca.c b/board/amcc/yucca/yucca.c
index af12839..65f7575 100644
--- a/board/amcc/yucca/yucca.c
+++ b/board/amcc/yucca/yucca.c
@@ -562,10 +562,11 @@
static long int yucca_probe_for_dimms(void)
{
- long int dimm_installed[MAXDIMMS];
- long int dimm_num, probe_result;
- long int dimms_found = 0;
- uchar dimm_addr = IIC0_DIMM0_ADDR;
+ int dimm_installed[MAXDIMMS];
+ int dimm_num, result;
+ int dimms_found = 0;
+ uchar dimm_addr = IIC0_DIMM0_ADDR;
+ uchar dimm_spd_data[MAX_SPD_BYTES];
for (dimm_num = 0; dimm_num < MAXDIMMS; dimm_num++) {
/* check if there is a chip at the dimm address */
@@ -577,12 +578,28 @@
dimm_addr = IIC0_DIMM1_ADDR;
break;
}
- probe_result = i2c_probe(dimm_addr);
- if (probe_result == 0) {
+ result = i2c_probe(dimm_addr);
+
+ memset(dimm_spd_data, 0, MAX_SPD_BYTES * sizeof(char));
+ if (result == 0) {
+ /* read first byte of SPD data, if there is any data */
+ result = i2c_read(dimm_addr, 0, 1, dimm_spd_data, 1);
+
+ if (result == 0) {
+ result = dimm_spd_data[0];
+ result = result > MAX_SPD_BYTES ?
+ MAX_SPD_BYTES : result;
+ result = i2c_read(dimm_addr, 0, 1,
+ dimm_spd_data, result);
+ }
+ }
+
+ if ((result == 0) &&
+ (dimm_spd_data[64] == MICRON_SPD_JEDEC_ID)) {
dimm_installed[dimm_num] = TRUE;
dimms_found++;
- debug("DIMM slot %d: DDR2 SDRAM detected\n",dimm_num);
+ debug("DIMM slot %d: DDR2 SDRAM detected\n", dimm_num);
} else {
dimm_installed[dimm_num] = FALSE;
debug("DIMM slot %d: Not populated or cannot sucessfully probe the DIMM\n", dimm_num);
diff --git a/board/amcc/yucca/yucca.h b/board/amcc/yucca/yucca.h
index 66f7584..4d13021 100644
--- a/board/amcc/yucca/yucca.h
+++ b/board/amcc/yucca/yucca.h
@@ -60,6 +60,9 @@
#define NUM_TLB_ENTRIES 64
+/* MICRON SPD JEDEC ID Code (first byte) - SPD data byte [64] */
+#define MICRON_SPD_JEDEC_ID 0x2c
+
/*----------------------------------------------------------------------------+
| TLB specific defines.
+----------------------------------------------------------------------------*/