Re: [PATCH v3 03/14] media: ov7670: hook s_power onto v4l2 core

On Thu, 2018-11-22 at 14:21 +0200, Sakari Ailus wrote:

Hi Lubomir,

On Tue, Nov 20, 2018 at 11:03:08AM +0100, Lubomir Rintel wrote:

quoted

The commit 71862f63f351 ("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>

---
Changes since v2:
- Restore the controls, format and frame rate on power on

 drivers/media/i2c/ov7670.c | 50 +++++++++++++++++++++++++++++++++-----
 1 file changed, 44 insertions(+), 6 deletions(-)

diff --git a/drivers/media/i2c/ov7670.c b/drivers/media/i2c/ov7670.c
index ead0c360df33..cbaab60aaaac 100644
--- a/drivers/media/i2c/ov7670.c
+++ b/drivers/media/i2c/ov7670.c

@@ -242,6 +242,7 @@ 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 */

@@ -1615,19 +1616,54 @@ 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;
 }
 

@@ -1660,6 +1696,7 @@ 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,
 #ifdef CONFIG_VIDEO_ADV_DEBUG
 	.g_register = ov7670_g_register,
 	.s_register = ov7670_s_register,

@@ -1825,6 +1862,7 @@ static int ov7670_probe(struct i2c_client *client,
 		else
 			return ret;
 	}
+
 	if (info->clk) {
 		ret = clk_prepare_enable(info->clk);
 		if (ret)

@@ -1841,7 +1879,7 @@ 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);

@@ -1929,7 +1967,7 @@ 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;

@@ -1945,7 +1983,7 @@ 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;
 }
 

Could you consider instead switching to runtime PM? A few drivers such as
the ov2685 driver does that already.

Yes, I'll take a look. Thanks for the suggestion. I didn't know such
thing exists, so it may take some time for me to grasp it though.

Take care,
Lubo