linux-kernel - Re: [PATCHv3] support for AD5820 camera auto-focus coil

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Date:	Tue, 24 May 2016 22:20:59 +0200
From:	Pavel Machek <pavel@....cz>
To:	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
Cc:	pali.rohar@...il.com, sre@...nel.org,
	kernel list <linux-kernel@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-omap@...r.kernel.org, tony@...mide.com, khilman@...nel.org,
	aaro.koskinen@....fi, patrikbachan@...il.com, serge@...lyn.com,
	linux-media@...r.kernel.org, mchehab@....samsung.com,
	sakari.ailus@....fi
Subject: Re: [PATCHv3] support for AD5820 camera auto-focus coil

Hi!

> >>devm_regulator_get()?
> >
> >I'd rather avoid devm_ here. Driver is simple enough to allow it.
> >
> 
> Now thinking about it, what would happen here if regulator_get() returns
> -EPROBE_DEFER? Wouldn't it be better to move regulator_get to the probe()
> function, something like:

Ok, I can do it.

Oh, and don't try to complain about newlines before returns. It looks
better this way.

> static int ad5820_probe(struct i2c_client *client,
> 			const struct i2c_device_id *devid)
> {
> 	struct ad5820_device *coil;
> 	int ret = 0;
> 
> 	coil = devm_kzalloc(sizeof(*coil), GFP_KERNEL);
> 	if (coil == NULL)
> 		return -ENOMEM;
> 
> 	coil->vana = devm_regulator_get(&client->dev, NULL);
> 	if (IS_ERR(coil->vana)) {
> 		ret = PTR_ERR(coil->vana);
> 		if (ret != -EPROBE_DEFER)
> 			dev_err(&client->dev, "could not get regulator for vana\n");
> 		return ret;
> 	}
> 
> 	mutex_init(&coil->power_lock);
> ...
> 
> with the appropriate changes to remove() because of the devm API
> 			usage.

Something like this?

diff --git a/drivers/media/i2c/ad5820.c b/drivers/media/i2c/ad5820.c
index f956bd3..f871366 100644
--- a/drivers/media/i2c/ad5820.c
+++ b/drivers/media/i2c/ad5820.c
@@ -8,7 +8,7 @@
  * Copyright (C) 2016 Pavel Machek <pavel@....cz>
  *
  * Contact: Tuukka Toivonen
- *          Sakari Ailus
+ *	    Sakari Ailus
  *
  * Based on af_d88.c by Texas Instruments.
  *
@@ -263,13 +263,6 @@ static int ad5820_init_controls(struct ad5820_device *coil)
 static int ad5820_registered(struct v4l2_subdev *subdev)
 {
 	struct ad5820_device *coil = to_ad5820_device(subdev);
-	struct i2c_client *client = v4l2_get_subdevdata(subdev);
-
-	coil->vana = regulator_get(&client->dev, "VANA");
-	if (IS_ERR(coil->vana)) {
-		dev_err(&client->dev, "could not get regulator for vana\n");
-		return -ENODEV;
-	}
 
 	return ad5820_init_controls(coil);
 }
@@ -367,10 +360,18 @@ static int ad5820_probe(struct i2c_client *client,
 	struct ad5820_device *coil;
 	int ret = 0;
 
-	coil = kzalloc(sizeof(*coil), GFP_KERNEL);
+	coil = devm_kzalloc(sizeof(*coil), GFP_KERNEL);
 	if (!coil)
 		return -ENOMEM;
 
+	coil->vana = devm_regulator_get(&client->dev, NULL);
+	if (IS_ERR(coil->vana)) {
+		ret = PTR_ERR(coil->vana);
+		if (ret != -EPROBE_DEFER)
+			dev_err(&client->dev, "could not get regulator for vana\n");
+		return ret;
+	}
+	
 	mutex_init(&coil->power_lock);
 
 	v4l2_i2c_subdev_init(&coil->subdev, client, &ad5820_ops);
@@ -390,10 +391,6 @@ static int ad5820_probe(struct i2c_client *client,
 
 cleanup:
 	media_entity_cleanup(&coil->subdev.entity);
-
-free:
-	kfree(coil);
-
 	return ret;
 }
 
@@ -405,11 +402,6 @@ static int __exit ad5820_remove(struct i2c_client *client)
 	v4l2_device_unregister_subdev(&coil->subdev);
 	v4l2_ctrl_handler_free(&coil->ctrls);
 	media_entity_cleanup(&coil->subdev.entity);
-	if (coil->vana)
-		regulator_put(coil->vana);
-
-	kfree(coil);
-
 	return 0;
 }
 


-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html