linux-kernel - [PATCH] pwm: Call pwm_enable() before pwm

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Date:	Thu, 23 Aug 2012 16:19:47 +0200 (CEST)
From:	Benoît Thébaudeau 
	<benoit.thebaudeau@...ansee.com>
To:	Thierry Reding <thierry.reding@...onic-design.de>,
	linux-kernel@...r.kernel.org, Sascha Hauer <kernel@...gutronix.de>,
	linux-arm-kernel@...ts.infradead.org,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-input@...r.kernel.org, Bryan Wu <bryan.wu@...onical.com>,
	Richard Purdie <rpurdie@...ys.net>, linux-leds@...r.kernel.org,
	Florian Tobias Schandinat <FlorianSchandinat@....de>,
	linux-fbdev@...r.kernel.org
Cc:	Benoît Thébaudeau 
	<benoit.thebaudeau@...ansee.com>
Subject: [PATCH] pwm: Call pwm_enable() before pwm_config()

Some PWM drivers enable the clock of the PWM peripheral in pwm_enable(). Hence,
for these drivers, a call to pwm_config() does not have any effect before
pwm_enable() has been called.

This patch fixes the PWM users to make sure that they call pwm_enable() before
pwm_config().

This fixes the first setting of brightness through sysfs that had no effect with
leds-pwm and the i.MX PWM driver.

Cc: Thierry Reding <thierry.reding@...onic-design.de>
Cc: <linux-kernel@...r.kernel.org>
Cc: Sascha Hauer <kernel@...gutronix.de>
Cc: <linux-arm-kernel@...ts.infradead.org>
Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: <linux-input@...r.kernel.org>
Cc: Bryan Wu <bryan.wu@...onical.com>
Cc: Richard Purdie <rpurdie@...ys.net>
Cc: <linux-leds@...r.kernel.org>
Cc: Florian Tobias Schandinat <FlorianSchandinat@....de>
Cc: <linux-fbdev@...r.kernel.org>
Cc: Benoît Thébaudeau <benoit.thebaudeau@...ansee.com>
Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@...ansee.com>
---
 .../drivers/input/misc/pwm-beeper.c                |    6 +++---
 .../drivers/leds/leds-pwm.c                        |    2 +-
 .../drivers/video/backlight/pwm_bl.c               |    2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git linux-next-c94456b.orig/drivers/input/misc/pwm-beeper.c linux-next-c94456b/drivers/input/misc/pwm-beeper.c
index fc84c8a..97d322b 100644
--- linux-next-c94456b.orig/drivers/input/misc/pwm-beeper.c
+++ linux-next-c94456b/drivers/input/misc/pwm-beeper.c
@@ -53,10 +53,10 @@ static int pwm_beeper_event(struct input_dev *input,
 		pwm_disable(beeper->pwm);
 	} else {
 		period = HZ_TO_NANOSECONDS(value);
-		ret = pwm_config(beeper->pwm, period / 2, period);
+		ret = pwm_enable(beeper->pwm);
 		if (ret)
 			return ret;
-		ret = pwm_enable(beeper->pwm);
+		ret = pwm_config(beeper->pwm, period / 2, period);
 		if (ret)
 			return ret;
 		beeper->period = period;
@@ -156,8 +156,8 @@ static int pwm_beeper_resume(struct device *dev)
 	struct pwm_beeper *beeper = dev_get_drvdata(dev);
 
 	if (beeper->period) {
-		pwm_config(beeper->pwm, beeper->period / 2, beeper->period);
 		pwm_enable(beeper->pwm);
+		pwm_config(beeper->pwm, beeper->period / 2, beeper->period);
 	}
 
 	return 0;
diff --git linux-next-c94456b.orig/drivers/leds/leds-pwm.c linux-next-c94456b/drivers/leds/leds-pwm.c
index f2e44c7..c2e0c22 100644
--- linux-next-c94456b.orig/drivers/leds/leds-pwm.c
+++ linux-next-c94456b/drivers/leds/leds-pwm.c
@@ -42,8 +42,8 @@ static void led_pwm_set(struct led_classdev *led_cdev,
 		pwm_config(led_dat->pwm, 0, period);
 		pwm_disable(led_dat->pwm);
 	} else {
-		pwm_config(led_dat->pwm, brightness * period / max, period);
 		pwm_enable(led_dat->pwm);
+		pwm_config(led_dat->pwm, brightness * period / max, period);
 	}
 }
 
diff --git linux-next-c94456b.orig/drivers/video/backlight/pwm_bl.c linux-next-c94456b/drivers/video/backlight/pwm_bl.c
index 995f016..a4bb95c 100644
--- linux-next-c94456b.orig/drivers/video/backlight/pwm_bl.c
+++ linux-next-c94456b/drivers/video/backlight/pwm_bl.c
@@ -65,8 +65,8 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
 
 		duty_cycle = pb->lth_brightness +
 		     (duty_cycle * (pb->period - pb->lth_brightness) / max);
-		pwm_config(pb->pwm, duty_cycle, pb->period);
 		pwm_enable(pb->pwm);
+		pwm_config(pb->pwm, duty_cycle, pb->period);
 	}
 
 	if (pb->notify_after)
--
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