drivers/regulator: fix a missing check of return value

BugLink: https://bugs.launchpad.net/bugs/1855313

[ Upstream commit 966e927b ]

If palmas_smps_read() fails, we should not use the read data in "reg"
which may contain random value. The fix inserts a check for the return
value of palmas_smps_read(): If it fails, we return the error code
upstream and stop using "reg".
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/regulator/palmas-regulator.c

@@ -435,13 +435,16 @@ static int palmas_ldo_write(struct palmas *palmas, unsigned int reg,
 static int palmas_set_mode_smps(struct regulator_dev *dev, unsigned int mode)
 {
 	int id = rdev_get_id(dev);
+	int ret;
 	struct palmas_pmic *pmic = rdev_get_drvdata(dev);
 	struct palmas_pmic_driver_data *ddata = pmic->palmas->pmic_ddata;
 	struct palmas_regs_info *rinfo = &ddata->palmas_regs_info[id];
 	unsigned int reg;
 	bool rail_enable = true;
 
-	palmas_smps_read(pmic->palmas, rinfo->ctrl_addr, &reg);
+	ret = palmas_smps_read(pmic->palmas, rinfo->ctrl_addr, &reg);
+	if (ret)
+		return ret;
 
 	reg &= ~PALMAS_SMPS12_CTRL_MODE_ACTIVE_MASK;