max8925_power: Do not read random data from chip registers

Reading the voltage, charge etc requires that we tell the chip
what property we want to read before reading it according to
maxim.

Signed-off-by: Philip Rakity <prakity@marvell.com>
Signed-off-by: Thomas Liu <Thomas.Liu@maxim-ic.com>
Tested-by: Ted Bennett <tbennett@marvell.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/power/max8925_power.c b/drivers/power/max8925_power.c
index 377d1e633b4a..d87032afcb5a 100644
--- a/drivers/power/max8925_power.c
+++ b/drivers/power/max8925_power.c
@@ -160,25 +160,31 @@ static irqreturn_t max8925_charger_handler(int irq, void *data)
 static int start_measure(struct max8925_power_info *info, int type)
 {
         unsigned char buf[2] = {0, 0};
+        int meas_cmd;
         int meas_reg = 0, ret;
 
         switch (type) {
         case MEASURE_VCHG:
+                meas_cmd = MAX8925_CMD_VCHG;
                 meas_reg = MAX8925_ADC_VCHG;
                 break;
         case MEASURE_VBBATT:
+                meas_cmd = MAX8925_CMD_VBBATT;
                 meas_reg = MAX8925_ADC_VBBATT;
                 break;
         case MEASURE_VMBATT:
+                meas_cmd = MAX8925_CMD_VMBATT;
                 meas_reg = MAX8925_ADC_VMBATT;
                 break;
         case MEASURE_ISNS:
+                meas_cmd = MAX8925_CMD_ISNS;
                 meas_reg = MAX8925_ADC_ISNS;
                 break;
         default:
                 return -EINVAL;
         }
 
+        max8925_reg_write(info->adc, meas_cmd, 0);
         max8925_bulk_read(info->adc, meas_reg, 2, buf);
         ret = ((buf[0]<<8) | buf[1]) >> 4;