cnss2: treat no wlan regulator as no error

If device tree doesn't configure any regulators for
device, means this device doesn't need extra regulator.
This case shall not be treated as an error.

Return a positive value for this case to allow caller to
make proper choice.

Change-Id: I7ead81b3915d16f966f94c9d916e0d67bc04fda0
CRs-Fixed: 3355141

cnss2/main.c

@@ -1251,7 +1251,7 @@ static int cnss_get_resources(struct cnss_plat_data *plat_priv)
 	int ret = 0;
 
 	ret = cnss_get_vreg_type(plat_priv, CNSS_VREG_PRIM);
-	if (ret) {
+	if (ret < 0) {
 		cnss_pr_err("Failed to get vreg, err = %d\n", ret);
 		goto out;
 	}

cnss2/pci.c

@@ -6205,7 +6205,7 @@ static int cnss_pci_probe(struct pci_dev *pci_dev,
 	}
 
 	ret = cnss_dev_specific_power_on(plat_priv);
-	if (ret)
+	if (ret < 0)
 		goto reset_ctx;
 
 	cnss_pci_of_reserved_mem_device_init(pci_priv);

cnss2/power.c

@@ -91,6 +91,7 @@ static struct cnss_clk_cfg cnss_clk_list[] = {
 #define CNSS_PMIC_AUTO_HEADROOM 16
 #define CNSS_IR_DROP_WAKE 30
 #define CNSS_IR_DROP_SLEEP 10
+#define VREG_NOTFOUND 1
 
 /**
  * enum cnss_aop_vreg_param: Voltage regulator TCS param
@@ -327,8 +328,10 @@ static struct cnss_vreg_cfg *get_vreg_list(u32 *vreg_list_size,
  * For multi-exchg dt node, get the required vregs' names from property
  * 'wlan_vregs', which is string array;
  *
- * if the property is present but no value is set, then no additional wlan
- * verg is required.
+ * If the property is not present or present but no value is set, then no
+ * additional wlan verg is required, function return VREG_NOTFOUND.
+ * If property is present with valid value, function return 0.
+ * Other cases a negative value is returned.
  *
  * For non-multi-exchg dt, go through all vregs in the static array
  * 'cnss_vreg_list'.
@@ -356,14 +359,19 @@ static int cnss_get_vreg(struct cnss_plat_data *plat_priv,
 		id_n = of_property_count_strings(dt_node,
 						 WLAN_VREGS_PROP);
 		if (id_n <= 0) {
-			if (id_n == -ENODATA) {
+			if (id_n == -ENODATA || id_n == -EINVAL) {
 				cnss_pr_dbg("No additional vregs for: %s:%lx\n",
 					    dt_node->name,
 					    plat_priv->device_id);
-				return 0;
+				/* By returning a positive value, give the caller a
+				 * chance to know no additional regulator is needed
+				 * by this device, and shall not treat this case as
+				 * an error.
+				 */
+				return VREG_NOTFOUND;
 			}
 
-			cnss_pr_err("property %s is invalid or missed: %s:%lx\n",
+			cnss_pr_err("property %s is invalid: %s:%lx\n",
 				    WLAN_VREGS_PROP, dt_node->name,
 				    plat_priv->device_id);
 			return -EINVAL;