media: ov7670: Add the ov7670_s_power function

Add the ov7670_s_power function which is responsible for
manipulating the power dowm mode through the PWDN pin and the reset
operation through the RESET pin, and keep it powered at all times.

[sakari.ailus@linux.intel.com: set pwdn_gpio direction only once]
Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/i2c/ov7670.c

@@ -1544,6 +1544,22 @@ static int ov7670_s_register(struct v4l2_subdev *sd, const struct v4l2_dbg_regis
 }
 #endif
 
+static int ov7670_s_power(struct v4l2_subdev *sd, int on)
+{
+	struct ov7670_info *info = to_state(sd);
+
+	if (info->pwdn_gpio)
+		gpiod_set_value(info->pwdn_gpio, !on);
+	if (on && info->resetb_gpio) {
+		gpiod_set_value(info->resetb_gpio, 1);
+		usleep_range(500, 1000);
+		gpiod_set_value(info->resetb_gpio, 0);
+		usleep_range(3000, 5000);
+	}
+
+	return 0;
+}
+
 static void ov7670_get_default_format(struct v4l2_subdev *sd,
 				      struct v4l2_mbus_framefmt *format)
 {
@@ -1694,23 +1710,25 @@ static int ov7670_probe(struct i2c_client *client,
 	if (ret)
 		return ret;
 
-	ret = ov7670_init_gpio(client, info);
-	if (ret)
-		goto clk_disable;
-
 	info->clock_speed = clk_get_rate(info->clk) / 1000000;
 	if (info->clock_speed < 10 || info->clock_speed > 48) {
 		ret = -EINVAL;
 		goto clk_disable;
 	}
 
+	ret = ov7670_init_gpio(client, info);
+	if (ret)
+		goto clk_disable;
+
+	ov7670_s_power(sd, 1);
+
 	/* Make sure it's an ov7670 */
 	ret = ov7670_detect(sd);
 	if (ret) {
 		v4l_dbg(1, debug, client,
 			"chip found @ 0x%x (%s) is not an ov7670 chip.\n",
 			client->addr << 1, client->adapter->name);
-		goto clk_disable;
+		goto power_off;
 	}
 	v4l_info(client, "chip found @ 0x%02x (%s)\n",
 			client->addr << 1, client->adapter->name);
@@ -1789,6 +1807,8 @@ static int ov7670_probe(struct i2c_client *client,
 #endif
 hdl_free:
 	v4l2_ctrl_handler_free(&info->hdl);
+power_off:
+	ov7670_s_power(sd, 0);
 clk_disable:
 	clk_disable_unprepare(info->clk);
 	return ret;
@@ -1806,6 +1826,7 @@ static int ov7670_remove(struct i2c_client *client)
 #if defined(CONFIG_MEDIA_CONTROLLER)
 	media_entity_cleanup(&info->sd.entity);
 #endif
+	ov7670_s_power(sd, 0);
 	return 0;
 }