[v3][PATCH 4/5] media: ov2640: add a master clock for sensor

---
v2 -> v3:
  1. should return PTR_ERR().

v1 -> v2:
  1. change the clock's name.
  2. Make the clock is mandatory.

 drivers/media/i2c/soc_camera/ov2640.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/media/i2c/soc_camera/ov2640.c

b/drivers/media/i2c/soc_camera/ov2640.c index e0bcf5b..055702c 100644

--- a/drivers/media/i2c/soc_camera/ov2640.c
+++ b/drivers/media/i2c/soc_camera/ov2640.c

@@ -13,6 +13,7 @@
  * published by the Free Software Foundation.
  */

+#include <linux/clk.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/i2c.h>

@@ -31,6 +32,7 @@

 #define VAL_SET(x, mask, rshift, lshift)  \
 		((((x) >> rshift) & mask) << lshift)
+
 /*
  * DSP registers
  * register offset for BANK_SEL == BANK_SEL_DSP

@@ -284,6 +286,7 @@ struct ov2640_priv {
 	struct v4l2_ctrl_handler	hdl;
 	u32	cfmt_code;
 	struct v4l2_clk			*clk;
+	struct clk			*master_clk;
 	const struct ov2640_win_size	*win;

 	struct soc_camera_subdev_desc	ssdd_dt;

@@ -746,6 +749,7 @@ static int ov2640_s_power(struct v4l2_subdev *sd, int

on) struct soc_camera_subdev_desc *ssdd = soc_camera_i2c_to_desc(client);
struct ov2640_priv *priv = to_ov2640(client);
 	struct v4l2_clk *clk;
+	int ret;

 	if (!priv->clk) {
 		clk = v4l2_clk_get(&client->dev, "mclk");

@@ -755,7 +759,20 @@ static int ov2640_s_power(struct v4l2_subdev *sd, int

on) priv->clk = clk;
 	}

-	return soc_camera_set_power(&client->dev, ssdd, priv->clk, on);
+	if (on) {
+		ret = clk_prepare_enable(priv->master_clk);
+		if (ret)
+			return ret;
+	} else {
+		clk_disable_unprepare(priv->master_clk);
+	}
+
+	ret = soc_camera_set_power(&client->dev, ssdd, priv->clk, on);
+
+	if (ret && on)
+		clk_disable_unprepare(priv->master_clk);
+
+	return ret;
 }

 /* Select the nearest higher resolution for capture */

@@ -1145,6 +1162,10 @@ static int ov2640_probe(struct i2c_client *client,
 			return ret;
 	}

+	priv->master_clk = devm_clk_get(&client->dev, "xvclk");
+	if (IS_ERR(priv->master_clk))
+		return PTR_ERR(priv->master_clk);
+
 	v4l2_i2c_subdev_init(&priv->subdev, client, &ov2640_subdev_ops);
 	v4l2_ctrl_handler_init(&priv->hdl, 2);
 	v4l2_ctrl_new_std(&priv->hdl, &ov2640_ctrl_ops,