From 7cd23384f6720b025100e71e68072de1a198eb5b Mon Sep 17 00:00:00 2001
From: moosecrap <admin@long-cat.net>
Date: Sun, 16 Feb 2025 22:28:16 -0800
Subject: [PATCH] Added --i2c command line option

---
 README.md   |  3 ++-
 evga-card.c | 11 ++++++++++-
 evga-card.h |  2 +-
 evga-icx.c  | 16 +++++++++++++---
 4 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 498d103..6d12709 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@
 This program allows you to read temperature sensors off of supported EVGA 30-series iCX3 video cards, as well as control the fans individually.
 
 ## Prerequisites
-A supported EVGA 30-series iCX3 card.  I have not done extensive testing but belive this is every model of their:
+A supported EVGA 30-series card with iCX3.  This includes:
 * RTX 3060 Ti
 * RTX 3070
 * RTX 3070 Ti
@@ -39,6 +39,7 @@ Note that when controlling fans directly through iCX3 they will fall offline fro
 
 ```text
 Available options:
+--i2c N      : Only probe I2C bus N instead of all (may help with stuttering with --watch)
 --gpu N      : Control only GPU N instead of all supported cards
 --fan SPEED  : Set all fans at once to SPEED (see below)
 --fanN SPEED : Set fan N (0-3) to SPEED
diff --git a/evga-card.c b/evga-card.c
index 41f8cd7..1f0bd6f 100644
--- a/evga-card.c
+++ b/evga-card.c
@@ -8,7 +8,7 @@
 
 /* Search all i2c device files for ones are on a PCI device of a supported GPU,
    and respond with the correct iCX3 version information */
-int find_evga_gpu_i2cs(struct card_info *infos, int max_gpus)
+int find_evga_gpu_i2cs(struct card_info *infos, int max_gpus, int i2c_bus)
 {
 	char i2c_devices_path[NAME_MAX];
 	char device_path[NAME_MAX];
@@ -20,6 +20,7 @@ int find_evga_gpu_i2cs(struct card_info *infos, int max_gpus)
 	struct dirent *ent;
 	
 	int num_gpus = 0;
+	int current_i2c_bus = -1;
 	unsigned short pci_vendor, pci_device, pci_subsystem_vendor, pci_subsystem_device = 0;
 	
 	/* Start looking for I2C adapters in /sys/bus/i2c/devices/ */
@@ -37,6 +38,14 @@ int find_evga_gpu_i2cs(struct card_info *infos, int max_gpus)
 		if(strncmp(ent->d_name, "i2c-", 4) != 0) 
 			continue;
 		
+		/* Only probe the specific device given (if provided) */
+		if (i2c_bus >= 0) {
+			sscanf(ent->d_name, "i2c-%i", &current_i2c_bus);
+			if (current_i2c_bus != i2c_bus)
+				continue;
+		}
+		
+		
 		strcpy(device_path, i2c_devices_path);
 		strcat(device_path, ent->d_name);
 		
diff --git a/evga-card.h b/evga-card.h
index 87353b2..79189bb 100644
--- a/evga-card.h
+++ b/evga-card.h
@@ -162,7 +162,7 @@ static struct gpu_pci_info evga_pci_ids[] =
 	{"EVGA GeForce RTX 3090 Ti FTW3 Ultra Gaming"          , NVIDIA_VEN,   NVIDIA_RTX3090TI_DEV,       EVGA_SUB_VEN,   EVGA_RTX3090TI_FTW3_ULTRA_GAMING_SUB_DEV      }
 };
 
-int find_evga_gpu_i2cs(struct card_info *infos, int max_gpus);
+int find_evga_gpu_i2cs(struct card_info *infos, int max_gpus, int i2c_bus);
 unsigned short read_pci_id(char *device_path, char *field);
 char *read_nvidia_pci_address(char *device_path);
 
diff --git a/evga-icx.c b/evga-icx.c
index 38ae0be..64cd1fb 100644
--- a/evga-icx.c
+++ b/evga-icx.c
@@ -24,7 +24,8 @@ char *header_start = "";
 char *header_end = "";
 
 static const char helpstring[] = "Available options:\n"
-                                 "--gpu N      : Control only GPU N instead of all supported cards\n"
+								 "--i2c N      : Only probe I2C bus N instead of all (may help with stuttering with --watch)\n"
+								 "--gpu N      : Control only GPU N instead of all supported cards\n"
 								 "--fan SPEED  : Set all fans at once to SPEED (see below)\n"
 								 "--fanN SPEED : Set fan N (0-3) to SPEED\n"
 								 "    SPEED may be one of the following:\n"
@@ -47,13 +48,22 @@ int main (int argc, char **argv)
 	int print_info = 0;
 	int compact = 0;
 	int gpu_num = -1;    /* Card to control */
+	int i2c_bus = -1;
 	int overwrite = 0;
 	unsigned int watch = 0;
 	char *fan_speed[ICX3_MAX_FANS] = {NULL}; 
 	
 	/* Input parsing */
 	for (int i = 1; i < argc; i++){
-		if (strcmp(argv[i], "--gpu") == 0) {
+		if (strcmp(argv[i], "--i2c") == 0) {
+			i++;
+			if (i < argc) {
+				i2c_bus = atoi(argv[i]);
+			} else {
+				printf(helpstring);
+				return -1;
+			}
+		} else if (strcmp(argv[i], "--gpu") == 0) {
 			i++;
 			if (i < argc) {
 				gpu_num = atoi(argv[i]);
@@ -119,7 +129,7 @@ int main (int argc, char **argv)
 	if (overwrite && !compact)
 		overwrite = 0;
 	
-	gpu_count = find_evga_gpu_i2cs(gpus, MAX_GPUS);
+	gpu_count = find_evga_gpu_i2cs(gpus, MAX_GPUS, i2c_bus);
 
 	if (gpu_count == -1) {
 		printf("Error scanning I2C devices\n");