Regulator: lp3972 cleanup

This patch includes below fixes based on Mark's comment.
 - Return actual error if i2c_smbus_read_byte_data() fail
 - Add spaces around bitwise AND operator(&) to improve readability
 - Add comment to explain why we need to update voltage change control register
   for LDO1 and LDO5
 - Logging the value for diagnostics if chip reported incorrect voltage value
 - Add __devinit annotation for setup_regulators()
 - Show system control register1 value if the value is mismatched
 - Logging the value for diagnostics if failed to detect device

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

1 files changed, 18 insertions, 7 deletions

diff --git a/drivers/regulator/lp3972.c b/drivers/regulator/lp3972.c
index 0d9b47569c1b..e07062fd0b42 100644
--- a/drivers/regulator/lp3972.c
+++ b/drivers/regulator/lp3972.c
@@ -192,7 +192,7 @@ static int lp3972_i2c_read(struct i2c_client *i2c, char reg, int count,
                 return -EIO;
         ret = i2c_smbus_read_byte_data(i2c, reg);
         if (ret < 0)
-                return -EIO;
+                return ret;
 
         *dest = ret;
         return 0;
@@ -215,7 +215,7 @@ static u8 lp3972_reg_read(struct lp3972 *lp3972, u8 reg)
         lp3972_i2c_read(lp3972->i2c, reg, 1, &val);
 
         dev_dbg(lp3972->dev, "reg read 0x%02x -> 0x%02x\n", (int)reg,
-                (unsigned)val&0xff);
+                (unsigned)val & 0xff);
 
         mutex_unlock(&lp3972->io_lock);
 
@@ -234,7 +234,7 @@ static int lp3972_set_bits(struct lp3972 *lp3972, u8 reg, u16 mask, u16 val)
         if (ret == 0) {
                 ret = lp3972_i2c_write(lp3972->i2c, reg, 1, &tmp);
                 dev_dbg(lp3972->dev, "reg write 0x%02x -> 0x%02x\n", (int)reg,
-                        (unsigned)val&0xff);
+                        (unsigned)val & 0xff);
         }
         mutex_unlock(&lp3972->io_lock);
 
@@ -320,6 +320,13 @@ static int lp3972_ldo_set_voltage(struct regulator_dev *dev,
         if (ret)
                 return ret;
 
+        /*
+         * LDO1 and LDO5 support voltage control by either target voltage1
+         * or target voltage2 register.
+         * We use target voltage1 register for LDO1 and LDO5 in this driver.
+         * We need to update voltage change control register(0x20) to enable
+         * LDO1 and LDO5 to change to their programmed target values.
+         */
         switch (ldo) {
         case LP3972_LDO1:
         case LP3972_LDO5:
@@ -401,7 +408,8 @@ static int lp3972_dcdc_get_voltage(struct regulator_dev *dev)
                 val = 1000 * buck_voltage_map[buck][reg];
         else {
                 val = 0;
-                dev_warn(&dev->dev, "chip reported incorrect voltage value.\n");
+                dev_warn(&dev->dev, "chip reported incorrect voltage value."
+                                    " reg = %d\n", reg);
         }
 
         return val;
@@ -523,7 +531,7 @@ static struct regulator_desc regulators[] = {
         },
 };
 
-static int setup_regulators(struct lp3972 *lp3972,
+static int __devinit setup_regulators(struct lp3972 *lp3972,
         struct lp3972_platform_data *pdata)
 {
         int i, err;
@@ -584,10 +592,13 @@ static int __devinit lp3972_i2c_probe(struct i2c_client *i2c,
 
         /* Detect LP3972 */
         ret = lp3972_i2c_read(i2c, LP3972_SYS_CONTROL1_REG, 1, &val);
-        if (ret == 0 && (val & SYS_CONTROL1_INIT_MASK) != SYS_CONTROL1_INIT_VAL)
+        if (ret == 0 &&
+                (val & SYS_CONTROL1_INIT_MASK) != SYS_CONTROL1_INIT_VAL) {
                 ret = -ENODEV;
+                dev_err(&i2c->dev, "chip reported: val = 0x%x\n", val);
+        }
         if (ret < 0) {
-                dev_err(&i2c->dev, "failed to detect device\n");
+                dev_err(&i2c->dev, "failed to detect device. ret = %d\n", ret);
                 goto err_detect;
         }