diff --git a/drivers/media/video/m5mols/m5mols.h b/drivers/media/video/m5mols/m5mols.h
index 5a8a858fdb2d..0265ea602280 100644
--- a/drivers/media/video/m5mols/m5mols.h
+++ b/drivers/media/video/m5mols/m5mols.h
@@ -174,8 +174,8 @@ struct m5mols_version {
  * @ver: information of the version
  * @cap: the capture mode attributes
  * @power: current sensor's power status
- * @ctrl_sync: true means all controls of the sensor are initialized
- * @int_capture: true means the capture interrupt is issued once
+ * @isp_ready: 1 when the ISP controller has completed booting
+ * @ctrl_sync: 1 when the control handler state is restored in H/W
  * @lock_ae: true means the Auto Exposure is locked
  * @lock_awb: true means the Aut WhiteBalance is locked
  * @resolution:	register value for current resolution
@@ -204,8 +204,11 @@ struct m5mols_info {
 
 	struct m5mols_version ver;
 	struct m5mols_capture cap;
-	bool power;
-	bool ctrl_sync;
+
+	unsigned int isp_ready:1;
+	unsigned int power:1;
+	unsigned int ctrl_sync:1;
+
 	bool lock_ae;
 	bool lock_awb;
 	u8 resolution;
@@ -213,7 +216,6 @@ struct m5mols_info {
 	int (*set_power)(struct device *dev, int on);
 };
 
-#define is_powered(__info) (__info->power)
 #define is_ctrl_synced(__info) (__info->ctrl_sync)
 #define is_available_af(__info)	(__info->ver.af)
 #define is_code(__code, __type) (__code == m5mols_default_ffmt[__type].code)
diff --git a/drivers/media/video/m5mols/m5mols_core.c b/drivers/media/video/m5mols/m5mols_core.c
index 070f04c39914..3c7556f40221 100644
--- a/drivers/media/video/m5mols/m5mols_core.c
+++ b/drivers/media/video/m5mols/m5mols_core.c
@@ -135,10 +135,13 @@ static u32 m5mols_swap_byte(u8 *data, u8 length)
  * @reg: combination of size, category and command for the I2C packet
  * @size: desired size of I2C packet
  * @val: read value
+ *
+ * Returns 0 on success, or else negative errno.
  */
 static int m5mols_read(struct v4l2_subdev *sd, u32 size, u32 reg, u32 *val)
 {
 	struct i2c_client *client = v4l2_get_subdevdata(sd);
+	struct m5mols_info *info = to_m5mols(sd);
 	u8 rbuf[M5MOLS_I2C_MAX_SIZE + 1];
 	u8 category = I2C_CATEGORY(reg);
 	u8 cmd = I2C_COMMAND(reg);
@@ -168,15 +171,17 @@ static int m5mols_read(struct v4l2_subdev *sd, u32 size, u32 reg, u32 *val)
 	usleep_range(200, 200);
 
 	ret = i2c_transfer(client->adapter, msg, 2);
-	if (ret < 0) {
-		v4l2_err(sd, "read failed: size:%d cat:%02x cmd:%02x. %d\n",
-			 size, category, cmd, ret);
-		return ret;
+
+	if (ret == 2) {
+		*val = m5mols_swap_byte(&rbuf[1], size);
+		return 0;
 	}
 
-	*val = m5mols_swap_byte(&rbuf[1], size);
+	if (info->isp_ready)
+		v4l2_err(sd, "read failed: size:%d cat:%02x cmd:%02x. %d\n",
+			 size, category, cmd, ret);
 
-	return 0;
+	return ret < 0 ? ret : -EIO;
 }
 
 int m5mols_read_u8(struct v4l2_subdev *sd, u32 reg, u8 *val)
@@ -229,10 +234,13 @@ int m5mols_read_u32(struct v4l2_subdev *sd, u32 reg, u32 *val)
  * m5mols_write - I2C command write function
  * @reg: combination of size, category and command for the I2C packet
  * @val: value to write
+ *
+ * Returns 0 on success, or else negative errno.
  */
 int m5mols_write(struct v4l2_subdev *sd, u32 reg, u32 val)
 {
 	struct i2c_client *client = v4l2_get_subdevdata(sd);
+	struct m5mols_info *info = to_m5mols(sd);
 	u8 wbuf[M5MOLS_I2C_MAX_SIZE + 4];
 	u8 category = I2C_CATEGORY(reg);
 	u8 cmd = I2C_COMMAND(reg);
@@ -263,13 +271,14 @@ int m5mols_write(struct v4l2_subdev *sd, u32 reg, u32 val)
 	usleep_range(200, 200);
 
 	ret = i2c_transfer(client->adapter, msg, 1);
-	if (ret < 0) {
-		v4l2_err(sd, "write failed: size:%d cat:%02x cmd:%02x. %d\n",
-			size, category, cmd, ret);
-		return ret;
-	}
+	if (ret == 1)
+		return 0;
 
-	return 0;
+	if (info->isp_ready)
+		v4l2_err(sd, "write failed: cat:%02x cmd:%02x ret:%d\n",
+			 category, cmd, ret);
+
+	return ret < 0 ? ret : -EIO;
 }
 
 /**
@@ -620,7 +629,7 @@ int m5mols_sync_controls(struct m5mols_info *info)
 			return ret;
 
 		v4l2_ctrl_handler_setup(&info->handle);
-		info->ctrl_sync = true;
+		info->ctrl_sync = 1;
 	}
 
 	return ret;
@@ -700,10 +709,10 @@ static int m5mols_sensor_power(struct m5mols_info *info, bool enable)
 	const struct m5mols_platform_data *pdata = info->pdata;
 	int ret;
 
-	if (enable) {
-		if (is_powered(info))
-			return 0;
+	if (info->power == enable)
+		return 0;
 
+	if (enable) {
 		if (info->set_power) {
 			ret = info->set_power(&client->dev, 1);
 			if (ret)
@@ -717,15 +726,11 @@ static int m5mols_sensor_power(struct m5mols_info *info, bool enable)
 		}
 
 		gpio_set_value(pdata->gpio_reset, !pdata->reset_polarity);
-		usleep_range(1000, 1000);
-		info->power = true;
+		info->power = 1;
 
 		return ret;
 	}
 
-	if (!is_powered(info))
-		return 0;
-
 	ret = regulator_bulk_disable(ARRAY_SIZE(supplies), supplies);
 	if (ret)
 		return ret;
@@ -734,8 +739,9 @@ static int m5mols_sensor_power(struct m5mols_info *info, bool enable)
 		info->set_power(&client->dev, 0);
 
 	gpio_set_value(pdata->gpio_reset, pdata->reset_polarity);
-	usleep_range(1000, 1000);
-	info->power = false;
+
+	info->isp_ready = 0;
+	info->power = 0;
 
 	return ret;
 }
@@ -748,21 +754,29 @@ int __attribute__ ((weak)) m5mols_update_fw(struct v4l2_subdev *sd,
 }
 
 /**
- * m5mols_sensor_armboot - Booting M-5MOLS internal ARM core.
+ * m5mols_fw_start - M-5MOLS internal ARM controller initialization
  *
- * Booting internal ARM core makes the M-5MOLS is ready for getting commands
- * with I2C. It's the first thing to be done after it powered up. It must wait
- * at least 520ms recommended by M-5MOLS datasheet, after executing arm booting.
+ * Execute the M-5MOLS internal ARM controller initialization sequence.
+ * This function should be called after the supply voltage has been
+ * applied and before any requests to the device are made.
  */
-static int m5mols_sensor_armboot(struct v4l2_subdev *sd)
+static int m5mols_fw_start(struct v4l2_subdev *sd)
 {
+	struct m5mols_info *info = to_m5mols(sd);
 	int ret;
 
-	ret = m5mols_write(sd, FLASH_CAM_START, REG_START_ARM_BOOT);
+	atomic_set(&info->irq_done, 0);
+	/* Wait until I2C slave is initialized in Flash Writer mode */
+	ret = m5mols_busy_wait(sd, FLASH_CAM_START, REG_IN_FLASH_MODE,
+			       M5MOLS_I2C_RDY_WAIT_FL | 0xff, -1);
+	if (!ret)
+		ret = m5mols_write(sd, FLASH_CAM_START, REG_START_ARM_BOOT);
+	if (!ret)
+		ret = m5mols_wait_interrupt(sd, REG_INT_MODE, 2000);
 	if (ret < 0)
 		return ret;
 
-	msleep(520);
+	info->isp_ready = 1;
 
 	ret = m5mols_get_version(sd);
 	if (!ret)
@@ -840,7 +854,7 @@ static int m5mols_s_power(struct v4l2_subdev *sd, int on)
 	if (on) {
 		ret = m5mols_sensor_power(info, true);
 		if (!ret)
-			ret = m5mols_sensor_armboot(sd);
+			ret = m5mols_fw_start(sd);
 		if (!ret)
 			ret = m5mols_init_controls(info);
 		if (ret)
@@ -869,7 +883,7 @@ static int m5mols_s_power(struct v4l2_subdev *sd, int on)
 	ret = m5mols_sensor_power(info, false);
 	if (!ret) {
 		v4l2_ctrl_handler_free(&info->handle);
-		info->ctrl_sync = false;
+		info->ctrl_sync = 0;
 	}
 
 	return ret;
diff --git a/drivers/media/video/m5mols/m5mols_reg.h b/drivers/media/video/m5mols/m5mols_reg.h
index d488add006de..ae4aced0f9b2 100644
--- a/drivers/media/video/m5mols/m5mols_reg.h
+++ b/drivers/media/video/m5mols/m5mols_reg.h
@@ -355,6 +355,7 @@
 
 /* Starts internal ARM core booting after power-up */
 #define FLASH_CAM_START		I2C_REG(CAT_FLASH, 0x12, 1)
-#define REG_START_ARM_BOOT	0x01
+#define REG_START_ARM_BOOT	0x01	/* write value */
+#define REG_IN_FLASH_MODE	0x00	/* read value */
 
 #endif	/* M5MOLS_REG_H */