media: i2c: ov2659: Use clk_{prepare_enable,disable_unprepare}() to set xvclk on/off

On some platform(imx6q), xvclk might not switch on in advance,
also for power save purpose, xvclk should not be always on.
so, add clk_prepare_enable(), clk_disable_unprepare() in driver
side to set xvclk on/off at proper stage.

Add following changes:
- add 'struct clk *clk;' in 'struct ov2659 {}'
- enable xvclk in ov2659_power_on()
- disable xvclk in ov2659_power_off()
Signed-off-by: Dillon Min <dillon.minfei@gmail.com>
Acked-by: Lad Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/i2c/ov2659.c

@@ -204,6 +204,7 @@ struct ov2659 {
 	struct i2c_client *client;
 	struct v4l2_ctrl_handler ctrls;
 	struct v4l2_ctrl *link_frequency;
+	struct clk *clk;
 	const struct ov2659_framesize *frame_size;
 	struct sensor_register *format_ctrl_regs;
 	struct ov2659_pll_ctrl pll;
@@ -1268,6 +1269,8 @@ static int ov2659_power_off(struct device *dev)
 
 	gpiod_set_value(ov2659->pwdn_gpio, 1);
 
+	clk_disable_unprepare(ov2659->clk);
+
 	return 0;
 }
 
@@ -1276,9 +1279,17 @@ static int ov2659_power_on(struct device *dev)
 	struct i2c_client *client = to_i2c_client(dev);
 	struct v4l2_subdev *sd = i2c_get_clientdata(client);
 	struct ov2659 *ov2659 = to_ov2659(sd);
+	int ret;
 
 	dev_dbg(&client->dev, "%s:\n", __func__);
 
+	ret = clk_prepare_enable(ov2659->clk);
+	if (ret) {
+		dev_err(&client->dev, "%s: failed to enable clock\n",
+			__func__);
+		return ret;
+	}
+
 	gpiod_set_value(ov2659->pwdn_gpio, 0);
 
 	if (ov2659->resetb_gpio) {
@@ -1423,7 +1434,6 @@ static int ov2659_probe(struct i2c_client *client)
 	const struct ov2659_platform_data *pdata = ov2659_get_pdata(client);
 	struct v4l2_subdev *sd;
 	struct ov2659 *ov2659;
-	struct clk *clk;
 	int ret;
 
 	if (!pdata) {
@@ -1438,11 +1448,11 @@ static int ov2659_probe(struct i2c_client *client)
 	ov2659->pdata = pdata;
 	ov2659->client = client;
 
-	clk = devm_clk_get(&client->dev, "xvclk");
-	if (IS_ERR(clk))
-		return PTR_ERR(clk);
+	ov2659->clk = devm_clk_get(&client->dev, "xvclk");
+	if (IS_ERR(ov2659->clk))
+		return PTR_ERR(ov2659->clk);
 
-	ov2659->xvclk_frequency = clk_get_rate(clk);
+	ov2659->xvclk_frequency = clk_get_rate(ov2659->clk);
 	if (ov2659->xvclk_frequency < 6000000 ||
 	    ov2659->xvclk_frequency > 27000000)
 		return -EINVAL;
@@ -1504,7 +1514,9 @@ static int ov2659_probe(struct i2c_client *client)
 	ov2659->frame_size = &ov2659_framesizes[2];
 	ov2659->format_ctrl_regs = ov2659_formats[0].format_ctrl_regs;
 
-	ov2659_power_on(&client->dev);
+	ret = ov2659_power_on(&client->dev);
+	if (ret < 0)
+		goto error;
 
 	ret = ov2659_detect(sd);
 	if (ret < 0)