media: ov7670: hook s_power onto v4l2 core

The commit 71862f63 ("media: ov7670: Add the ov7670_s_power function")
added a power control routing. However, it was not good enough to use as
a s_power() callback: it merely flipped on the power GPIOs without
restoring the register settings.

Fix this now and register an actual power callback.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/i2c/ov7670.c

@@ -243,6 +243,7 @@ struct ov7670_info {
 	struct ov7670_format_struct *fmt;  /* Current format */
 	struct ov7670_win_size *wsize;
 	struct clk *clk;
+	int on;
 	struct gpio_desc *resetb_gpio;
 	struct gpio_desc *pwdn_gpio;
 	unsigned int mbus_config;	/* Media bus configuration flags */
@@ -1617,19 +1618,54 @@ 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)
+static void ov7670_power_on(struct v4l2_subdev *sd)
 {
 	struct ov7670_info *info = to_state(sd);
 
+	if (info->on)
+		return;
+
 	if (info->pwdn_gpio)
-		gpiod_set_value(info->pwdn_gpio, !on);
-	if (on && info->resetb_gpio) {
+		gpiod_set_value(info->pwdn_gpio, 0);
+	if (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);
 	}
 
+	info->on = true;
+}
+
+static void ov7670_power_off(struct v4l2_subdev *sd)
+{
+	struct ov7670_info *info = to_state(sd);
+
+	if (!info->on)
+		return;
+
+	if (info->pwdn_gpio)
+		gpiod_set_value(info->pwdn_gpio, 1);
+
+	info->on = false;
+}
+
+static int ov7670_s_power(struct v4l2_subdev *sd, int on)
+{
+	struct ov7670_info *info = to_state(sd);
+
+	if (info->on == on)
+		return 0;
+
+	if (on) {
+		ov7670_power_on (sd);
+		ov7670_apply_fmt(sd);
+		ov7675_apply_framerate(sd);
+		v4l2_ctrl_handler_setup(&info->hdl);
+	} else {
+		ov7670_power_off (sd);
+	}
+
 	return 0;
 }
 
@@ -1662,6 +1698,7 @@ static int ov7670_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
 static const struct v4l2_subdev_core_ops ov7670_core_ops = {
 	.reset = ov7670_reset,
 	.init = ov7670_init,
+	.s_power = ov7670_s_power,
 	.log_status = v4l2_ctrl_subdev_log_status,
 	.subscribe_event = v4l2_ctrl_subdev_subscribe_event,
 	.unsubscribe_event = v4l2_event_subdev_unsubscribe,
@@ -1826,6 +1863,7 @@ static int ov7670_probe(struct i2c_client *client,
 		else
 			return ret;
 	}
+
 	if (info->clk) {
 		ret = clk_prepare_enable(info->clk);
 		if (ret)
@@ -1842,7 +1880,7 @@ static int ov7670_probe(struct i2c_client *client,
 	if (ret)
 		goto clk_disable;
 
-	ov7670_s_power(sd, 1);
+	ov7670_power_on(sd);
 
 	/* Make sure it's an ov7670 */
 	ret = ov7670_detect(sd);
@@ -1930,7 +1968,7 @@ static int ov7670_probe(struct i2c_client *client,
 hdl_free:
 	v4l2_ctrl_handler_free(&info->hdl);
 power_off:
-	ov7670_s_power(sd, 0);
+	ov7670_power_off(sd);
 clk_disable:
 	clk_disable_unprepare(info->clk);
 	return ret;
@@ -1946,7 +1984,7 @@ static int ov7670_remove(struct i2c_client *client)
 	v4l2_ctrl_handler_free(&info->hdl);
 	clk_disable_unprepare(info->clk);
 	media_entity_cleanup(&info->sd.entity);
-	ov7670_s_power(sd, 0);
+	ov7670_power_off(sd);
 	return 0;
 }