[PATCH usb-next] phy: realtek: usb: add the error handler for nvmem_cell_read

[Stanley Chang <stanley_chang@realtek.com>]

There are following smatch warning:
drivers/phy/realtek/phy-rtk-usb2.c:901 get_phy_data_by_efuse()
error: 'buf' dereferencing possible ERR_PTR()
drivers/phy/realtek/phy-rtk-usb2.c:942 get_phy_data_by_efuse()
error: 'buf' dereferencing possible ERR_PTR()

drivers/phy/realtek/phy-rtk-usb3.c:460
get_phy_data_by_efuse() error: 'buf' dereferencing possible ERR_PTR()

The nvmem_cell_read may fail to read. So, driver must handle failure cases.

Fixes: 134e6d25f6bd ("phy: realtek: usb: Add driver for the Realtek SoC USB 2.0 PHY")
Fixes: adda6e82a7de ("phy: realtek: usb: Add driver for the Realtek SoC USB 3.0 PHY")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-phy/e7ff2870-c30c-4d8d-a7a9-d2d6a4962eb5@kadam.mountain/
Signed-off-by: Stanley Chang <stanley_chang@realtek.com>
---
 drivers/phy/realtek/phy-rtk-usb2.c | 14 ++++++++------
 drivers/phy/realtek/phy-rtk-usb3.c |  7 ++++---
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/phy/realtek/phy-rtk-usb2.c b/drivers/phy/realtek/phy-rtk-usb2.c
index ed47a1ce5d9c..5e7ee060b404 100644
--- a/drivers/phy/realtek/phy-rtk-usb2.c
+++ b/drivers/phy/realtek/phy-rtk-usb2.c
@@ -898,9 +898,10 @@ static int get_phy_data_by_efuse(struct rtk_phy *rtk_phy,
 		size_t buf_size;
 
 		buf = nvmem_cell_read(cell, &buf_size);
-		value = buf[0] & phy_cfg->dc_driving_mask;
-
-		kfree(buf);
+		if (!IS_ERR(buf)) {
+			value = buf[0] & phy_cfg->dc_driving_mask;
+			kfree(buf);
+		}
 		nvmem_cell_put(cell);
 	}
 
@@ -939,9 +940,10 @@ static int get_phy_data_by_efuse(struct rtk_phy *rtk_phy,
 		size_t buf_size;
 
 		buf = nvmem_cell_read(cell, &buf_size);
-		value = buf[0] & phy_cfg->dc_disconnect_mask;
-
-		kfree(buf);
+		if (!IS_ERR(buf)) {
+			value = buf[0] & phy_cfg->dc_disconnect_mask;
+			kfree(buf);
+		}
 		nvmem_cell_put(cell);
 	}
 
diff --git a/drivers/phy/realtek/phy-rtk-usb3.c b/drivers/phy/realtek/phy-rtk-usb3.c
index 6050f1ef4f6b..7881f908aade 100644
--- a/drivers/phy/realtek/phy-rtk-usb3.c
+++ b/drivers/phy/realtek/phy-rtk-usb3.c
@@ -457,9 +457,10 @@ static int get_phy_data_by_efuse(struct rtk_phy *rtk_phy,
 		size_t buf_size;
 
 		buf = nvmem_cell_read(cell, &buf_size);
-		value = buf[0] & USB_U3_TX_LFPS_SWING_TRIM_MASK;
-
-		kfree(buf);
+		if (!IS_ERR(buf)) {
+			value = buf[0] & USB_U3_TX_LFPS_SWING_TRIM_MASK;
+			kfree(buf);
+		}
 		nvmem_cell_put(cell);
 	}
 
-- 
2.34.1