EDAC/skx_common: Use driver decoder first

The performance of driver decoder[1] is better than the performance
of firmware decoder[2], especially on frequent correctable errors.

So use the driver decoder first, fall back to firmware decoder if
the driver decoder is unavailable. Also rename the function pointer
skx_decode to driver_decode (better name to contrast with adxl_decode).

[1] Decode errors by extracting error information from registers of
    memory controllers and/or MCA bank registers.

[2] Decode errors by calling ACPI DSM methods.
Co-developed-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Youquan Song <youquan.song@intel.com>
Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/all/20220901194310.115427-1-tony.luck@intel.com/

drivers/edac/skx_base.c

@@ -714,8 +714,13 @@ static int __init skx_init(void)
 
 	skx_set_decode(skx_decode, skx_show_retry_rd_err_log);
 
-	if (nvdimm_count && skx_adxl_get() == -ENODEV)
-		skx_printk(KERN_NOTICE, "Only decoding DDR4 address!\n");
+	if (nvdimm_count && skx_adxl_get() != -ENODEV) {
+		skx_set_decode(NULL, skx_show_retry_rd_err_log);
+	} else {
+		if (nvdimm_count)
+			skx_printk(KERN_NOTICE, "Only decoding DDR4 address!\n");
+		skx_set_decode(skx_decode, skx_show_retry_rd_err_log);
+	}
 
 	/* Ensure that the OPSTATE is set correctly for POLL or NMI */
 	opstate_init();

drivers/edac/skx_common.c

@@ -40,7 +40,7 @@ static char *adxl_msg;
 static unsigned long adxl_nm_bitmap;
 
 static char skx_msg[MSG_SIZE];
-static skx_decode_f skx_decode;
+static skx_decode_f driver_decode;
 static skx_show_retry_log_f skx_show_retry_rd_err_log;
 static u64 skx_tolm, skx_tohm;
 static LIST_HEAD(dev_edac_list);
@@ -173,6 +173,8 @@ static bool skx_adxl_decode(struct decoded_addr *res, bool error_in_1st_level_me
 			break;
 	}
 
+	res->decoded_by_adxl = true;
+
 	return true;
 }
 
@@ -183,7 +185,7 @@ void skx_set_mem_cfg(bool mem_cfg_2lm)
 
 void skx_set_decode(skx_decode_f decode, skx_show_retry_log_f show_retry_log)
 {
-	skx_decode = decode;
+	driver_decode = decode;
 	skx_show_retry_rd_err_log = show_retry_log;
 }
 
@@ -591,7 +593,7 @@ static void skx_mce_output_error(struct mem_ctl_info *mci,
 			break;
 		}
 	}
-	if (adxl_component_count) {
+	if (res->decoded_by_adxl) {
 		len = snprintf(skx_msg, MSG_SIZE, "%s%s err_code:0x%04x:0x%04x %s",
 			 overflow ? " OVERFLOW" : "",
 			 (uncorrected_error && recoverable) ? " recoverable" : "",
@@ -651,11 +653,11 @@ int skx_mce_check_error(struct notifier_block *nb, unsigned long val,
 	memset(&res, 0, sizeof(res));
 	res.addr = mce->addr;
 
-	if (adxl_component_count) {
-		if (!skx_adxl_decode(&res, skx_error_in_1st_level_mem(mce)))
+	/* Try driver decoder first */
+	if (!(driver_decode && driver_decode(&res))) {
+		/* Then try firmware decoder (ACPI DSM methods) */
+		if (!(adxl_component_count && skx_adxl_decode(&res, skx_error_in_1st_level_mem(mce))))
 			return NOTIFY_DONE;
-	} else if (!skx_decode || !skx_decode(&res)) {
-		return NOTIFY_DONE;
 	}
 
 	mci = res.dev->imc[res.imc].mci;

drivers/edac/skx_common.h

@@ -136,6 +136,7 @@ struct decoded_addr {
 	int	column;
 	int	bank_address;
 	int	bank_group;
+	bool	decoded_by_adxl;
 };
 
 struct res_config {