[4.2.y-ckt stable] Patch "Input: pwm-beeper - fix - scheduling while atomic" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    Input: pwm-beeper - fix - scheduling while atomic

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt12.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 99a14fd19fc5c8bfaa3898e3e529001559ef5ead Mon Sep 17 00:00:00 2001
From: Manfred Schlaegl <manfred.schlaegl at gmx.at>
Date: Fri, 27 May 2016 16:36:36 -0700
Subject: Input: pwm-beeper - fix - scheduling while atomic

commit f49cf3b8b4c841457244c461c66186a719e13bcc upstream.

Pwm config may sleep so defer it using a worker.

On a Freescale i.MX53 based board we ran into "BUG: scheduling while
atomic" because input_inject_event locks interrupts, but
imx_pwm_config_v2 sleeps.

Tested on Freescale i.MX53 SoC with 4.6.0.

Signed-off-by: Manfred Schlaegl <manfred.schlaegl at gmx.at>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov at gmail.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/input/misc/pwm-beeper.c | 69 ++++++++++++++++++++++++++++-------------
 1 file changed, 48 insertions(+), 21 deletions(-)

diff --git a/drivers/input/misc/pwm-beeper.c b/drivers/input/misc/pwm-beeper.c
index e82edf8..9021725 100644
--- a/drivers/input/misc/pwm-beeper.c
+++ b/drivers/input/misc/pwm-beeper.c
@@ -20,21 +20,40 @@
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
 #include <linux/slab.h>
+#include <linux/workqueue.h>

 struct pwm_beeper {
 	struct input_dev *input;
 	struct pwm_device *pwm;
+	struct work_struct work;
 	unsigned long period;
 };

 #define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))

+static void __pwm_beeper_set(struct pwm_beeper *beeper)
+{
+	unsigned long period = beeper->period;
+
+	if (period) {
+		pwm_config(beeper->pwm, period / 2, period);
+		pwm_enable(beeper->pwm);
+	} else
+		pwm_disable(beeper->pwm);
+}
+
+static void pwm_beeper_work(struct work_struct *work)
+{
+	struct pwm_beeper *beeper =
+		container_of(work, struct pwm_beeper, work);
+
+	__pwm_beeper_set(beeper);
+}
+
 static int pwm_beeper_event(struct input_dev *input,
 			    unsigned int type, unsigned int code, int value)
 {
-	int ret = 0;
 	struct pwm_beeper *beeper = input_get_drvdata(input);
-	unsigned long period;

 	if (type != EV_SND || value < 0)
 		return -EINVAL;
@@ -49,22 +68,31 @@ static int pwm_beeper_event(struct input_dev *input,
 		return -EINVAL;
 	}

-	if (value == 0) {
-		pwm_disable(beeper->pwm);
-	} else {
-		period = HZ_TO_NANOSECONDS(value);
-		ret = pwm_config(beeper->pwm, period / 2, period);
-		if (ret)
-			return ret;
-		ret = pwm_enable(beeper->pwm);
-		if (ret)
-			return ret;
-		beeper->period = period;
-	}
+	if (value == 0)
+		beeper->period = 0;
+	else
+		beeper->period = HZ_TO_NANOSECONDS(value);
+
+	schedule_work(&beeper->work);

 	return 0;
 }

+static void pwm_beeper_stop(struct pwm_beeper *beeper)
+{
+	cancel_work_sync(&beeper->work);
+
+	if (beeper->period)
+		pwm_disable(beeper->pwm);
+}
+
+static void pwm_beeper_close(struct input_dev *input)
+{
+	struct pwm_beeper *beeper = input_get_drvdata(input);
+
+	pwm_beeper_stop(beeper);
+}
+
 static int pwm_beeper_probe(struct platform_device *pdev)
 {
 	unsigned long pwm_id = (unsigned long)dev_get_platdata(&pdev->dev);
@@ -87,6 +115,8 @@ static int pwm_beeper_probe(struct platform_device *pdev)
 		goto err_free;
 	}

+	INIT_WORK(&beeper->work, pwm_beeper_work);
+
 	beeper->input = input_allocate_device();
 	if (!beeper->input) {
 		dev_err(&pdev->dev, "Failed to allocate input device\n");
@@ -106,6 +136,7 @@ static int pwm_beeper_probe(struct platform_device *pdev)
 	beeper->input->sndbit[0] = BIT(SND_TONE) | BIT(SND_BELL);

 	beeper->input->event = pwm_beeper_event;
+	beeper->input->close = pwm_beeper_close;

 	input_set_drvdata(beeper->input, beeper);

@@ -135,7 +166,6 @@ static int pwm_beeper_remove(struct platform_device *pdev)

 	input_unregister_device(beeper->input);

-	pwm_disable(beeper->pwm);
 	pwm_free(beeper->pwm);

 	kfree(beeper);
@@ -147,8 +177,7 @@ static int __maybe_unused pwm_beeper_suspend(struct device *dev)
 {
 	struct pwm_beeper *beeper = dev_get_drvdata(dev);

-	if (beeper->period)
-		pwm_disable(beeper->pwm);
+	pwm_beeper_stop(beeper);

 	return 0;
 }
@@ -157,10 +186,8 @@ static int __maybe_unused 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);
-	}
+	if (beeper->period)
+		__pwm_beeper_set(beeper);

 	return 0;
 }
--
2.7.4