net: hns: Fix for variable may be used uninitialized warnings

When !CONFIG_REGMAP hns throws compiler warnings since
dsaf_read_syscon ignores the return result from regmap_read,
which allows val to be uninitialized.

Fixes: 86897c960b49 ("net: hns: add syscon operation for dsaf")
Reported-by: Jason Gunthorpe <[e-mail]>
Signed-off-by: Huazhong Tan <[e-mail]>
Signed-off-by: Yunsheng Lin <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/hisilicon/hns/hns_dsaf_misc.c

···
 
 static u32 dsaf_read_sub(struct dsaf_device *dsaf_dev, u32 reg)
 {
-	u32 ret;
+	u32 ret = 0;
+	int err;
 
-	if (dsaf_dev->sub_ctrl)
-		ret = dsaf_read_syscon(dsaf_dev->sub_ctrl, reg);
-	else
+	if (dsaf_dev->sub_ctrl) {
+		err = dsaf_read_syscon(dsaf_dev->sub_ctrl, reg, &ret);
+		if (err)
+			dev_err(dsaf_dev->dev, "dsaf_read_syscon error %d!\n",
+				err);
+	} else {
 		ret = dsaf_read_reg(dsaf_dev->sc_base, reg);
+	}
 
 	return ret;
 }
···
 static int cpld_set_led_id(struct hns_mac_cb *mac_cb,
 			   enum hnae_led_state status)
 {
+	u32 val = 0;
+	int ret;
+
 	if (!mac_cb->cpld_ctrl)
 		return 0;
 
 	switch (status) {
 	case HNAE_LED_ACTIVE:
-		mac_cb->cpld_led_value =
-			dsaf_read_syscon(mac_cb->cpld_ctrl,
-					 mac_cb->cpld_ctrl_reg);
-		dsaf_set_bit(mac_cb->cpld_led_value, DSAF_LED_ANCHOR_B,
-			     CPLD_LED_ON_VALUE);
+		ret = dsaf_read_syscon(mac_cb->cpld_ctrl, mac_cb->cpld_ctrl_reg,
+				       &val);
+		if (ret)
+			return ret;
+
+		dsaf_set_bit(val, DSAF_LED_ANCHOR_B, CPLD_LED_ON_VALUE);
 		dsaf_write_syscon(mac_cb->cpld_ctrl, mac_cb->cpld_ctrl_reg,
-				  mac_cb->cpld_led_value);
+				  val);
+		mac_cb->cpld_led_value = val;
 		break;
 	case HNAE_LED_INACTIVE:
 		dsaf_set_bit(mac_cb->cpld_led_value, DSAF_LED_ANCHOR_B,
···
 
 int hns_mac_get_sfp_prsnt(struct hns_mac_cb *mac_cb, int *sfp_prsnt)
 {
+	u32 val = 0;
+	int ret;
+
 	if (!mac_cb->cpld_ctrl)
 		return -ENODEV;
 
-	*sfp_prsnt = !dsaf_read_syscon(mac_cb->cpld_ctrl, mac_cb->cpld_ctrl_reg
-					+ MAC_SFP_PORT_OFFSET);
+	ret = dsaf_read_syscon(mac_cb->cpld_ctrl,
+			       mac_cb->cpld_ctrl_reg + MAC_SFP_PORT_OFFSET,
+			       &val);
+	if (ret)
+		return ret;
 
+	*sfp_prsnt = !val;
 	return 0;
 }
 
···
 #define RX_CSR(lane, reg) ((0x4080 + (reg) * 0x0002 + (lane) * 0x0200) * 2)
 	u64 reg_offset = RX_CSR(lane_id[mac_cb->mac_id], 0);
 
-	int sfp_prsnt;
+	int sfp_prsnt = 0;
 	int ret = hns_mac_get_sfp_prsnt(mac_cb, &sfp_prsnt);
 
 	if (!mac_cb->phy_dev) {
···
 	}
 
 	if (mac_cb->serdes_ctrl) {
-		u32 origin;
+		u32 origin = 0;
 
 		if (!AE_IS_VER1(mac_cb->dsaf_dev->dsaf_ver)) {
 #define HILINK_ACCESS_SEL_CFG		0x40008
···
 						  HILINK_ACCESS_SEL_CFG, 3);
 		}
 
-		origin = dsaf_read_syscon(mac_cb->serdes_ctrl, reg_offset);
+		ret = dsaf_read_syscon(mac_cb->serdes_ctrl, reg_offset,
+				       &origin);
+		if (ret)
+			return ret;
 
 		dsaf_set_field(origin, 1ull << 10, 10, en);
 		dsaf_write_syscon(mac_cb->serdes_ctrl, reg_offset, origin);

drivers/net/ethernet/hisilicon/hns/hns_dsaf_reg.h

···
 	regmap_write(base, reg, value);
 }
 
-static inline u32 dsaf_read_syscon(struct regmap *base, u32 reg)
+static inline int dsaf_read_syscon(struct regmap *base, u32 reg, u32 *val)
 {
-	unsigned int val;
-
-	regmap_read(base, reg, &val);
-	return val;
+	return regmap_read(base, reg, val);
 }
 
 #define dsaf_read_dev(a, reg) \