[coreboot] [PATCH] Some K8 revF RAM SPD refactoring

[Carl-Daniel Hailfinger]

Hi Ward,

I wanted to calculate the optimal timing for any setup with mixed DIMMs
where the timing parameters may be compatible but not identical.
This patch is a step in the right direction (hopefully). I think Marc
already reviewed parts of it last year, but I couldn't find the
conversation anymore.

Warning: The spec is horribly backwards in some places, and the code
sort of inherits this. I spent a few days figuring out why the old code
even worked, and then I noticed it wasn't as bad as it originally looked.

Feel free to comment, fix, apply, rip to shreds.

Signed-off-by: Carl-Daniel Hailfinger

Index: LinuxBIOSv2-asus_m2a-vm/src/northbridge/amd/amdk8/raminit_f.c
===================================================================
--- LinuxBIOSv2-asus_m2a-vm/src/northbridge/amd/amdk8/raminit_f.c	(Revision 4614)
+++ LinuxBIOSv2-asus_m2a-vm/src/northbridge/amd/amdk8/raminit_f.c	(Arbeitskopie)
@@ -39,7 +39,7 @@
 #error This file needs CONFIG_USE_PRINTK_IN_CAR
 #endif

-#define RAM_TIMING_DEBUG 0
+#define RAM_TIMING_DEBUG 1

#if RAM_TIMING_DEBUG == 1
 #define printk_raminit printk_debug
@@ -1499,7 +1499,8 @@
    		}
    		if (value0 != value1) {
    			printk_raminit("SPD values differ between channel 0/1 for byte %i\n", addr);
-				goto single_channel;
+				printk_raminit("Ignoring the differences for now!\n", addr);
+				//goto single_channel;
    		}
    	}
    }
@@ -1786,6 +1787,51 @@
    return 0;
 }

+int check_spd_latency_available(u32 spd_device, unsigned min_cycle_time, unsigned min_latency)
+{
+	int latencies;
+	int latency;
+	int index;
+	int value;
+
+	latencies = spd_read_byte(spd_device, SPD_CAS_LAT);
+	if (latencies < 0)
+		return -1;
+	if (latencies == 0)
+		return 1;
+
+	/* Compute the lowest cas latency supported */
+	latency = log2(latencies) -2;
+
+	/* Walk through searching for the selected latency */
+	for (index = 0; index < 3; index++, latency++) {
+		if (!(latencies & (1 << latency))) {
+			continue;
+		}
+		if (latency == min_latency)
+			break;
+	}
+	/* If I can't find the latency or my index is bad error */
+	if ((latency != min_latency) || (index >= 3)) {
+		return -2;
+	}
+
+	/* Read the min_cycle_time for this latency */
+	value = spd_read_byte(spd_device, latency_indicies[index]);
+	if (value < 0)
+		return -1;
+
+	value = convert_to_linear(value);
+	/* All is good if the selected clock speed
+	 * is what I need or slower.
+	 */
+	if (value <= min_cycle_time)
+		return 1;
+
+	/* That didn't work out... */
+	return -2;
+}
+
 static struct spd_set_memclk_result spd_set_memclk(const struct mem_controller *ctrl, struct mem_info *meminfo)
 {
    /* Compute the minimum cycle time for these dimms */
@@ -1856,10 +1902,6 @@
    printk_raminit("3 min_latency: %08x\n", min_latency);

for (i = 0; (i < DIMM_SOCKETS); i++) {
-		int latencies;
-		int latency;
-		int index;
-		int value;
    	u32 spd_device = ctrl->channel0[i];

if (!(meminfo->dimm_mask & (1 << i))) {
@@ -1870,42 +1912,17 @@
    		}
    	}

-		latencies = spd_read_byte(spd_device, SPD_CAS_LAT);
-		if (latencies < 0) goto hw_error;
-		if (latencies == 0) {
+		switch (check_spd_latency_available(spd_device, min_cycle_time, min_latency)) {
+		case -2:
+			/* We have an error, disable the dimm */
+			meminfo->dimm_mask = disable_dimm(ctrl, i, meminfo);
+			break;
+		case -1:
+			goto hw_error;
+			break;
+		case 1:
    		continue;
    	}
-
-		/* Compute the lowest cas latency supported */
-		latency = log2(latencies) -2;
-
-		/* Walk through searching for the selected latency */
-		for (index = 0; index < 3; index++, latency++) {
-			if (!(latencies & (1 << latency))) {
-				continue;
-			}
-			if (latency == min_latency)
-				break;
-		}
-		/* If I can't find the latency or my index is bad error */
-		if ((latency != min_latency) || (index >= 3)) {
-			goto dimm_err;
-		}
-
-		/* Read the min_cycle_time for this latency */
-		value = spd_read_byte(spd_device, latency_indicies[index]);
-		if (value < 0) goto hw_error;
-
-		value = convert_to_linear(value);
-		/* All is good if the selected clock speed
-		 * is what I need or slower.
-		 */
-		if (value <= min_cycle_time) {
-			continue;
-		}
-		/* Otherwise I have an error, disable the dimm */
-	dimm_err:
-		meminfo->dimm_mask = disable_dimm(ctrl, i, meminfo);
    }

printk_raminit("4 min_cycle_time: %08x\n", min_cycle_time);