[PATCH 02/11] media: ov7670: control clock along with power

[Lubomir Rintel]

This provides more power saving when the sensor is off.

While at that, do the delay on power/clock enable even if the sensor driver
itself doesn't control the GPIOs. This is required for the OLPC XO-1
platform, that lacks the proper power/reset properties in its DT, but
needs the delay after the sensor is clocked up.

Signed-off-by: Lubomir Rintel <lkund...@v3.sk>
---
 drivers/media/i2c/ov7670.c | 37 +++++++++++++++++++++----------------
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
index d87f2362bf40..a3e72c62382c 100644
--- a/drivers/media/i2c/ov7670.c
+++ b/drivers/media/i2c/ov7670.c
@@ -241,6 +241,7 @@ struct ov7670_info {
        struct v4l2_mbus_framefmt format;
        struct ov7670_format_struct *fmt;  /* Current format */
        struct clk *clk;
+       int on;
        struct gpio_desc *resetb_gpio;
        struct gpio_desc *pwdn_gpio;
        unsigned int mbus_config;       /* Media bus configuration flags */
@@ -1610,15 +1611,26 @@ 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)
+               clk_prepare_enable(info->clk);
+       else
+               clk_disable_unprepare(info->clk);
+
        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);
        }
 
+       if (on && (info->pwdn_gpio || info->resetb_gpio || info->clk))
+               usleep_range(3000, 5000);
+
+       info->on = on;
        return 0;
 }
 
@@ -1817,24 +1829,20 @@ static int ov7670_probe(struct i2c_client *client,
                else
                        return ret;
        }
-       if (info->clk) {
-               ret = clk_prepare_enable(info->clk);
-               if (ret)
-                       return ret;
+       ret = ov7670_init_gpio(client, info);
+       if (ret)
+               return ret;
+
+       ov7670_s_power(sd, 1);
 
+       if (info->clk) {
                info->clock_speed = clk_get_rate(info->clk) / 1000000;
                if (info->clock_speed < 10 || info->clock_speed > 48) {
                        ret = -EINVAL;
-                       goto clk_disable;
+                       goto power_off;
                }
        }
 
-       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) {
@@ -1913,6 +1921,7 @@ static int ov7670_probe(struct i2c_client *client,
        if (ret < 0)
                goto entity_cleanup;
 
+       ov7670_s_power(sd, 0);
        return 0;
 
 entity_cleanup:
@@ -1921,12 +1930,9 @@ static int ov7670_probe(struct i2c_client *client,
        v4l2_ctrl_handler_free(&info->hdl);
 power_off:
        ov7670_s_power(sd, 0);
-clk_disable:
-       clk_disable_unprepare(info->clk);
        return ret;
 }
 
-
 static int ov7670_remove(struct i2c_client *client)
 {
        struct v4l2_subdev *sd = i2c_get_clientdata(client);
@@ -1934,7 +1940,6 @@ static int ov7670_remove(struct i2c_client *client)
 
        v4l2_async_unregister_subdev(sd);
        v4l2_ctrl_handler_free(&info->hdl);
-       clk_disable_unprepare(info->clk);
        media_entity_cleanup(&info->sd.entity);
        ov7670_s_power(sd, 0);
        return 0;
-- 
2.19.1