[PATCH v2 02/11] media: ov7670: control clock along with power

From: Lubomir Rintel
Date: Sun Nov 11 2018 - 19:35:55 EST


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 <lkundrak@xxxxx>
---
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