[PATCH] amd64_edac: Rewrite unganged mode code of f10_early_channel_count

[wan wei <onewayforever@gmail.com>]

Hi,
     I rechecked the f10_early_channel_count function, and found more
bugs in unganged mode. This patch will fix  bugs under following
conditions,
    a. only one DIMM in each channelof the node,
    b. two DIMMs are populated in the same channel of the node,
    c. there is no DIMM in a node(other than node 0),
    a and b  mean both dbam should be checked in any condition,  and c
means even channels==0 is ok.

the patch has been tested and works well in  this  4 ways machine:
   node 0:  2 DIMMS on each channel
   node11: no DIMMS
   node2:  2 DIMM on the chanel 0
   node3:  one DIMM on each channel

thanks :-)

Signed-off-by: Wan Wei<wanwei@mail.dawning.com.cn>

---
 drivers/edac/amd64_edac.c |   46 ++++++++++++++------------------------------
 1 files changed, 15 insertions(+), 31 deletions(-)

diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index e2a10bc..7a328fa 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c
@@ -1200,6 +1200,7 @@ static int f10_early_channel_count(struct amd64_pvt *pvt)
 {
 	int err = 0, channels = 0;
 	u32 dbam;
+	int i;

 	err = pci_read_config_dword(pvt->dram_f2_ctl, F10_DCLR_0, &pvt->dclr0);
 	if (err)
@@ -1236,40 +1237,23 @@ static int f10_early_channel_count(struct
amd64_pvt *pvt)
 	if (err)
 		goto err_reg;

-	if (DBAM_DIMM(0, dbam) > 0)
-		channels++;
-	if (DBAM_DIMM(1, dbam) > 0)
-		channels++;
-	if (DBAM_DIMM(2, dbam) > 0)
-		channels++;
-	if (DBAM_DIMM(3, dbam) > 0)
-		channels++;
-
-	/* If more than 2 DIMMs are present, then we have 2 channels */
-	if (channels > 2)
-		channels = 2;
-	else if (channels == 0) {
-		/* No DIMMs on DCT0, so look at DCT1 */
-		err = pci_read_config_dword(pvt->dram_f2_ctl, DBAM1, &dbam);
-		if (err)
-			goto err_reg;
-
-		if (DBAM_DIMM(0, dbam) > 0)
+	for (i = 0; i < 4; i++) {
+		if (DBAM_DIMM(i, dbam) > 0) {
 			channels++;
-		if (DBAM_DIMM(1, dbam) > 0)
-			channels++;
-		if (DBAM_DIMM(2, dbam) > 0)
-			channels++;
-		if (DBAM_DIMM(3, dbam) > 0)
-			channels++;
-
-		if (channels > 2)
-			channels = 2;
+			break;
+		}
 	}

-	/* If we found ALL 0 values, then assume just ONE DIMM-ONE Channel */
-	if (channels == 0)
-		channels = 1;
+	err = pci_read_config_dword(pvt->dram_f2_ctl, DBAM1, &dbam);
+	if (err)
+		goto err_reg;
+
+	for (i = 0; i < 4; i++) {
+		if (DBAM_DIMM(i, dbam) > 0) {
+			channels++;
+			break;
+		}
+	}

 	debugf0("MCT channel count: %d\n", channels);

-- 
1.4.4.2