i7300_edac: Fix memory detection in single mode

When the machine is on single mode, only branch 0 channel 0
is valid. However, the code is not honouring it:

[ 1952.639341] EDAC DEBUG: i7300_get_mc_regs: Memory controller operating on single mode
...
[ 1952.639351] EDAC DEBUG: i7300_init_csrows: 		AMB-present CH0 = 0x1:
[ 1952.639353] EDAC DEBUG: i7300_init_csrows: 		AMB-present CH1 = 0x0:
[ 1952.639355] EDAC DEBUG: i7300_init_csrows: 		AMB-present CH2 = 0x0:
[ 1952.639358] EDAC DEBUG: i7300_init_csrows: 		AMB-present CH3 = 0x0:
...
[ 1952.639360] EDAC DEBUG: decode_mtr: 	MTR0 CH0: DIMMs are Present (mtr)
[ 1952.639362] EDAC DEBUG: decode_mtr: 		WIDTH: x8
[ 1952.639363] EDAC DEBUG: decode_mtr: 		ELECTRICAL THROTTLING is enabled
[ 1952.639364] EDAC DEBUG: decode_mtr: 		NUMBANK: 4 bank(s)
[ 1952.639366] EDAC DEBUG: decode_mtr: 		NUMRANK: single
[ 1952.639367] EDAC DEBUG: decode_mtr: 		NUMROW: 16,384 - 14 rows
[ 1952.639368] EDAC DEBUG: decode_mtr: 		NUMCOL: 1,024 - 10 columns
[ 1952.639370] EDAC DEBUG: decode_mtr: 		SIZE: 512 MB
[ 1952.639371] EDAC DEBUG: decode_mtr: 		ECC code is 8-byte-over-32-byte SECDED+ code
[ 1952.639373] EDAC DEBUG: decode_mtr: 		Scrub algorithm for x8 is on enhanced mode
[ 1952.639374] EDAC DEBUG: decode_mtr: 	MTR0 CH1: DIMMs are Present (mtr)
[ 1952.639376] EDAC DEBUG: decode_mtr: 		WIDTH: x8
[ 1952.639377] EDAC DEBUG: decode_mtr: 		ELECTRICAL THROTTLING is enabled
[ 1952.639379] EDAC DEBUG: decode_mtr: 		NUMBANK: 4 bank(s)
[ 1952.639380] EDAC DEBUG: decode_mtr: 		NUMRANK: single
[ 1952.639381] EDAC DEBUG: decode_mtr: 		NUMROW: 16,384 - 14 rows
[ 1952.639383] EDAC DEBUG: decode_mtr: 		NUMCOL: 1,024 - 10 columns
[ 1952.639384] EDAC DEBUG: decode_mtr: 		SIZE: 512 MB
[ 1952.639385] EDAC DEBUG: decode_mtr: 		ECC code is 8-byte-over-32-byte SECDED+ code
[ 1952.639387] EDAC DEBUG: decode_mtr: 		Scrub algorithm for x8 is on enhanced mode
...
[ 1952.639449] EDAC DEBUG: print_dimm_size:               channel 0 | channel 1 | channel 2 | channel 3 |
[ 1952.639451] EDAC DEBUG: print_dimm_size: -------------------------------------------------------------
[ 1952.639453] EDAC DEBUG: print_dimm_size: csrow/SLOT 0   512 MB   |  512 MB   |    0 MB   |    0 MB   |
[ 1952.639456] EDAC DEBUG: print_dimm_size: csrow/SLOT 1     0 MB   |    0 MB   |    0 MB   |    0 MB   |
[ 1952.639458] EDAC DEBUG: print_dimm_size: csrow/SLOT 2     0 MB   |    0 MB   |    0 MB   |    0 MB   |
[ 1952.639460] EDAC DEBUG: print_dimm_size: csrow/SLOT 3     0 MB   |    0 MB   |    0 MB   |    0 MB   |
[ 1952.639462] EDAC DEBUG: print_dimm_size: csrow/SLOT 4     0 MB   |    0 MB   |    0 MB   |    0 MB   |
[ 1952.639464] EDAC DEBUG: print_dimm_size: csrow/SLOT 5     0 MB   |    0 MB   |    0 MB   |    0 MB   |
[ 1952.639466] EDAC DEBUG: print_dimm_size: csrow/SLOT 6     0 MB   |    0 MB   |    0 MB   |    0 MB   |
[ 1952.639468] EDAC DEBUG: print_dimm_size: csrow/SLOT 7     0 MB   |    0 MB   |    0 MB   |    0 MB   |
[ 1952.639470] EDAC DEBUG: print_dimm_size: -------------------------------------------------------------

Instead of detecting a single memory at channel 0, it is showing
twice the memory.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/edac/i7300_edac.c

@@ -750,15 +750,23 @@ static int i7300_init_csrows(struct mem_ctl_info *mci)
 	struct i7300_dimm_info *dinfo;
 	int rc = -ENODEV;
 	int mtr;
-	int ch, branch, slot, channel;
+	int ch, branch, slot, channel, max_channel, max_branch;
 	struct dimm_info *dimm;
 
 	pvt = mci->pvt_info;
 
 	edac_dbg(2, "Memory Technology Registers:\n");
 
+	if (IS_SINGLE_MODE(pvt->mc_settings_a)) {
+		max_branch = 1;
+		max_channel = 1;
+	} else {
+		max_branch = MAX_BRANCHES;
+		max_channel = MAX_CH_PER_BRANCH;
+	}
+
 	/* Get the AMB present registers for the four channels */
-	for (branch = 0; branch < MAX_BRANCHES; branch++) {
+	for (branch = 0; branch < max_branch; branch++) {
 		/* Read and dump branch 0's MTRs */
 		channel = to_channel(0, branch);
 		pci_read_config_word(pvt->pci_dev_2x_0_fbd_branch[branch],
@@ -767,6 +775,9 @@ static int i7300_init_csrows(struct mem_ctl_info *mci)
 		edac_dbg(2, "\t\tAMB-present CH%d = 0x%x:\n",
 			 channel, pvt->ambpresent[channel]);
 
+		if (max_channel == 1)
+			continue;
+
 		channel = to_channel(1, branch);
 		pci_read_config_word(pvt->pci_dev_2x_0_fbd_branch[branch],
 				     AMBPRESENT_1,
@@ -778,11 +789,11 @@ static int i7300_init_csrows(struct mem_ctl_info *mci)
 	/* Get the set of MTR[0-7] regs by each branch */
 	for (slot = 0; slot < MAX_SLOTS; slot++) {
 		int where = mtr_regs[slot];
-		for (branch = 0; branch < MAX_BRANCHES; branch++) {
+		for (branch = 0; branch < max_branch; branch++) {
 			pci_read_config_word(pvt->pci_dev_2x_0_fbd_branch[branch],
 					where,
 					&pvt->mtr[slot][branch]);
-			for (ch = 0; ch < MAX_CH_PER_BRANCH; ch++) {
+			for (ch = 0; ch < max_channel; ch++) {
 				int channel = to_channel(ch, branch);
 
 				dimm = EDAC_DIMM_PTR(mci->layers, mci->dimms,