Patchwork [2/2] pwm-backlight: switch to gpiod interface

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Submitter Alexandre Courbot
Date Feb. 27, 2014, 5:53 a.m.
Message ID <1393480414-19473-3-git-send-email-acourbot@nvidia.com>
Download mbox | patch
Permalink /patch/324690/
State Accepted
Headers show

Comments

Alexandre Courbot - Feb. 27, 2014, 5:53 a.m.
Switch to the new gpiod interface, which allows to handle GPIO
properties such as active low transparently and removes a whole bunch of
code.

There are still a couple of users of this driver that rely on passing
the enable GPIO number through platform data, so a fallback mechanism
using a GPIO number is still available to avoid breaking them. It will
be removed once current users have switched to the GPIO lookup tables
provided by the gpiod interface.

Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
---
 drivers/video/backlight/pwm_bl.c | 72 +++++++++++++++++-----------------------
 include/linux/pwm_backlight.h    |  5 +--
 2 files changed, 32 insertions(+), 45 deletions(-)
Thierry Reding - May 7, 2014, 8:18 a.m.
On Thu, Feb 27, 2014 at 02:53:34PM +0900, Alexandre Courbot wrote:
> Switch to the new gpiod interface, which allows to handle GPIO
> properties such as active low transparently and removes a whole bunch of
> code.
> 
> There are still a couple of users of this driver that rely on passing
> the enable GPIO number through platform data, so a fallback mechanism
> using a GPIO number is still available to avoid breaking them. It will
> be removed once current users have switched to the GPIO lookup tables
> provided by the gpiod interface.
> 
> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
> ---
>  drivers/video/backlight/pwm_bl.c | 72 +++++++++++++++++-----------------------
>  include/linux/pwm_backlight.h    |  5 +--
>  2 files changed, 32 insertions(+), 45 deletions(-)

I've applied this with two tiny changes, see below. Please shout if you
think that's a bad idea.

> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
[...]
> @@ -256,8 +238,6 @@ static int pwm_backlight_probe(struct platform_device *pdev)
[...]
> +	pb->enable_gpio = devm_gpiod_get(&pdev->dev, "enable");
> +	if (IS_ERR(pb->enable_gpio)) {
> +		ret = PTR_ERR(pb->enable_gpio);
> +		if (ret == -ENOENT) {
> +			pb->enable_gpio = NULL;
> +			ret = 0;
> +		} else {
> +			goto err_alloc;
> +		}

I dropped the ret = 0 here because all error paths set it explicitly and
the non-error path never uses it. Now all branches have a single
statement and therefore the braces can be dropped.

> +	/*
> +	 * Compatibility fallback for drivers still using the integer GPIO
> +	 * platform data. Must go away soon.
> +	 */
> +	if (pb->enable_gpio == NULL && gpio_is_valid(data->enable_gpio)) {

Changed the first condition to !pb->enable_gpio for consistency.

Thierry
Alexandre Courbot - May 7, 2014, 8:39 a.m.
On Wed, May 7, 2014 at 5:18 PM, Thierry Reding <thierry.reding@gmail.com> wrote:
> On Thu, Feb 27, 2014 at 02:53:34PM +0900, Alexandre Courbot wrote:
>> Switch to the new gpiod interface, which allows to handle GPIO
>> properties such as active low transparently and removes a whole bunch of
>> code.
>>
>> There are still a couple of users of this driver that rely on passing
>> the enable GPIO number through platform data, so a fallback mechanism
>> using a GPIO number is still available to avoid breaking them. It will
>> be removed once current users have switched to the GPIO lookup tables
>> provided by the gpiod interface.
>>
>> Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
>> ---
>>  drivers/video/backlight/pwm_bl.c | 72 +++++++++++++++++-----------------------
>>  include/linux/pwm_backlight.h    |  5 +--
>>  2 files changed, 32 insertions(+), 45 deletions(-)
>
> I've applied this with two tiny changes, see below. Please shout if you
> think that's a bad idea.

I'm fine with both changes. Thanks for picking these two guys!

Alex.

>
>> diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
> [...]
>> @@ -256,8 +238,6 @@ static int pwm_backlight_probe(struct platform_device *pdev)
> [...]
>> +     pb->enable_gpio = devm_gpiod_get(&pdev->dev, "enable");
>> +     if (IS_ERR(pb->enable_gpio)) {
>> +             ret = PTR_ERR(pb->enable_gpio);
>> +             if (ret == -ENOENT) {
>> +                     pb->enable_gpio = NULL;
>> +                     ret = 0;
>> +             } else {
>> +                     goto err_alloc;
>> +             }
>
> I dropped the ret = 0 here because all error paths set it explicitly and
> the non-error path never uses it. Now all branches have a single
> statement and therefore the braces can be dropped.
>
>> +     /*
>> +      * Compatibility fallback for drivers still using the integer GPIO
>> +      * platform data. Must go away soon.
>> +      */
>> +     if (pb->enable_gpio == NULL && gpio_is_valid(data->enable_gpio)) {
>
> Changed the first condition to !pb->enable_gpio for consistency.
>
> Thierry
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Patch

diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index b75201ff46f6..533057688d93 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -10,8 +10,8 @@ 
  * published by the Free Software Foundation.
  */
 
+#include <linux/gpio/consumer.h>
 #include <linux/gpio.h>
-#include <linux/of_gpio.h>
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
@@ -32,8 +32,7 @@  struct pwm_bl_data {
 	unsigned int		*levels;
 	bool			enabled;
 	struct regulator	*power_supply;
-	int			enable_gpio;
-	unsigned long		enable_gpio_flags;
+	struct gpio_desc	*enable_gpio;
 	unsigned int		scale;
 	int			(*notify)(struct device *,
 					  int brightness);
@@ -54,12 +53,8 @@  static void pwm_backlight_power_on(struct pwm_bl_data *pb, int brightness)
 	if (err < 0)
 		dev_err(pb->dev, "failed to enable power supply\n");
 
-	if (gpio_is_valid(pb->enable_gpio)) {
-		if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW)
-			gpio_set_value(pb->enable_gpio, 0);
-		else
-			gpio_set_value(pb->enable_gpio, 1);
-	}
+	if (pb->enable_gpio)
+		gpiod_set_value(pb->enable_gpio, 1);
 
 	pwm_enable(pb->pwm);
 	pb->enabled = true;
@@ -73,12 +68,8 @@  static void pwm_backlight_power_off(struct pwm_bl_data *pb)
 	pwm_config(pb->pwm, 0, pb->period);
 	pwm_disable(pb->pwm);
 
-	if (gpio_is_valid(pb->enable_gpio)) {
-		if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW)
-			gpio_set_value(pb->enable_gpio, 1);
-		else
-			gpio_set_value(pb->enable_gpio, 0);
-	}
+	if (pb->enable_gpio)
+		gpiod_set_value(pb->enable_gpio, 0);
 
 	regulator_disable(pb->power_supply);
 	pb->enabled = false;
@@ -148,7 +139,6 @@  static int pwm_backlight_parse_dt(struct device *dev,
 				  struct platform_pwm_backlight_data *data)
 {
 	struct device_node *node = dev->of_node;
-	enum of_gpio_flags flags;
 	struct property *prop;
 	int length;
 	u32 value;
@@ -189,14 +179,6 @@  static int pwm_backlight_parse_dt(struct device *dev,
 		data->max_brightness--;
 	}
 
-	data->enable_gpio = of_get_named_gpio_flags(node, "enable-gpios", 0,
-						    &flags);
-	if (data->enable_gpio == -EPROBE_DEFER)
-		return -EPROBE_DEFER;
-
-	if (gpio_is_valid(data->enable_gpio) && (flags & OF_GPIO_ACTIVE_LOW))
-		data->enable_gpio_flags |= PWM_BACKLIGHT_GPIO_ACTIVE_LOW;
-
 	return 0;
 }
 
@@ -256,8 +238,6 @@  static int pwm_backlight_probe(struct platform_device *pdev)
 	} else
 		pb->scale = data->max_brightness;
 
-	pb->enable_gpio = data->enable_gpio;
-	pb->enable_gpio_flags = data->enable_gpio_flags;
 	pb->notify = data->notify;
 	pb->notify_after = data->notify_after;
 	pb->check_fb = data->check_fb;
@@ -265,26 +245,39 @@  static int pwm_backlight_probe(struct platform_device *pdev)
 	pb->dev = &pdev->dev;
 	pb->enabled = false;
 
-	if (gpio_is_valid(pb->enable_gpio)) {
-		unsigned long flags;
-
-		if (pb->enable_gpio_flags & PWM_BACKLIGHT_GPIO_ACTIVE_LOW)
-			flags = GPIOF_OUT_INIT_HIGH;
-		else
-			flags = GPIOF_OUT_INIT_LOW;
+	pb->enable_gpio = devm_gpiod_get(&pdev->dev, "enable");
+	if (IS_ERR(pb->enable_gpio)) {
+		ret = PTR_ERR(pb->enable_gpio);
+		if (ret == -ENOENT) {
+			pb->enable_gpio = NULL;
+			ret = 0;
+		} else {
+			goto err_alloc;
+		}
+	}
 
-		ret = gpio_request_one(pb->enable_gpio, flags, "enable");
+	/*
+	 * Compatibility fallback for drivers still using the integer GPIO
+	 * platform data. Must go away soon.
+	 */
+	if (pb->enable_gpio == NULL && gpio_is_valid(data->enable_gpio)) {
+		ret = devm_gpio_request_one(&pdev->dev, data->enable_gpio,
+					    GPIOF_OUT_INIT_HIGH, "enable");
 		if (ret < 0) {
 			dev_err(&pdev->dev, "failed to request GPIO#%d: %d\n",
-				pb->enable_gpio, ret);
+				data->enable_gpio, ret);
 			goto err_alloc;
 		}
+		pb->enable_gpio = gpio_to_desc(data->enable_gpio);
 	}
 
+	if (pb->enable_gpio)
+		gpiod_direction_output(pb->enable_gpio, 1);
+
 	pb->power_supply = devm_regulator_get(&pdev->dev, "power");
 	if (IS_ERR(pb->power_supply)) {
 		ret = PTR_ERR(pb->power_supply);
-		goto err_gpio;
+		goto err_alloc;
 	}
 
 	pb->pwm = devm_pwm_get(&pdev->dev, NULL);
@@ -295,7 +288,7 @@  static int pwm_backlight_probe(struct platform_device *pdev)
 		if (IS_ERR(pb->pwm)) {
 			dev_err(&pdev->dev, "unable to request legacy PWM\n");
 			ret = PTR_ERR(pb->pwm);
-			goto err_gpio;
+			goto err_alloc;
 		}
 	}
 
@@ -320,7 +313,7 @@  static int pwm_backlight_probe(struct platform_device *pdev)
 	if (IS_ERR(bl)) {
 		dev_err(&pdev->dev, "failed to register backlight\n");
 		ret = PTR_ERR(bl);
-		goto err_gpio;
+		goto err_alloc;
 	}
 
 	if (data->dft_brightness > data->max_brightness) {
@@ -336,9 +329,6 @@  static int pwm_backlight_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, bl);
 	return 0;
 
-err_gpio:
-	if (gpio_is_valid(pb->enable_gpio))
-		gpio_free(pb->enable_gpio);
 err_alloc:
 	if (data->exit)
 		data->exit(&pdev->dev);
diff --git a/include/linux/pwm_backlight.h b/include/linux/pwm_backlight.h
index 2de2e275b2cb..efdd9227a49c 100644
--- a/include/linux/pwm_backlight.h
+++ b/include/linux/pwm_backlight.h
@@ -6,9 +6,6 @@ 
 
 #include <linux/backlight.h>
 
-/* TODO: convert to gpiod_*() API once it has been merged */
-#define PWM_BACKLIGHT_GPIO_ACTIVE_LOW	(1 << 0)
-
 struct platform_pwm_backlight_data {
 	int pwm_id;
 	unsigned int max_brightness;
@@ -16,8 +13,8 @@  struct platform_pwm_backlight_data {
 	unsigned int lth_brightness;
 	unsigned int pwm_period_ns;
 	unsigned int *levels;
+	/* TODO remove once all users are switched to gpiod_* API */
 	int enable_gpio;
-	unsigned long enable_gpio_flags;
 	int (*init)(struct device *dev);
 	int (*notify)(struct device *dev, int brightness);
 	void (*notify_after)(struct device *dev, int brightness);