Commit 0af5e4c3 authored by Russell King's avatar Russell King
Browse files

MFD: ucb1x00-ts: fix resume failure 



If the ucb1x00 touchscreen is resumed while the touchscreen is being
touched, the main thread stops responding.  This occurs because two
things happen:

1. When we suspended, we were woken up, and executed the loop.
   Finding that the touchscreen was not pressed, we prepare to
   schedule for a maximum timeout, before being stopped in
   try_to_freeze().

2. an irq occurs, we disable the irq, and mark it as disabled,
   and wake the thread.  This wake occurs while the thread is
   still within __refrigerator()

3. The thread is unfrozen, and __refrigerator() sets the threads
   state back to INTERRUPTIBLE.

We then drop into schedule_timeout() with an infinite timeout and the
IRQ disabled.  This prevents any further screen touches activating
the thread.

Fix this by using kthread_freezable_should_stop() which handles the
freezing issues for us outside of the hotspot where the task state
matters.  Include a flag to ignore the touchscreen until it is
released to avoid sending unintended data to the application.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent c23bb602

drivers/mfd/ucb1x00-ts.c

+5 −27
Original line number Diff line number Diff line
@@ -47,7 +47,6 @@ struct ucb1x00_ts { 
	u16			x_res;

	u16			y_res;



	unsigned int		restart:1;

	unsigned int		adcsync:1;

};
@@ -207,15 +206,17 @@ static int ucb1x00_thread(void *_ts) 
{

	struct ucb1x00_ts *ts = _ts;

	DECLARE_WAITQUEUE(wait, current);

	bool frozen, ignore = false;

	int valid = 0;



	set_freezable();

	add_wait_queue(&ts->irq_wait, &wait);

	while (!kthread_should_stop()) {

	while (!kthread_freezable_should_stop(&frozen)) {

		unsigned int x, y, p;

		signed long timeout;



		ts->restart = 0;

		if (frozen)

			ignore = true;



		ucb1x00_adc_enable(ts->ucb);
@@ -258,7 +259,7 @@ static int ucb1x00_thread(void *_ts) 
			 * space.  We therefore leave it to user space

			 * to do any filtering they please.

			 */

			if (!ts->restart) {

			if (!ignore) {

				ucb1x00_ts_evt_add(ts, p, x, y);

				valid = 1;

			}
@@ -267,8 +268,6 @@ static int ucb1x00_thread(void *_ts) 
			timeout = HZ / 100;

		}



		try_to_freeze();



		schedule_timeout(timeout);

	}
@@ -340,26 +339,6 @@ static void ucb1x00_ts_close(struct input_dev *idev) 
	ucb1x00_disable(ts->ucb);

}



#ifdef CONFIG_PM

static int ucb1x00_ts_resume(struct ucb1x00_dev *dev)

{

	struct ucb1x00_ts *ts = dev->priv;



	if (ts->rtask != NULL) {

		/*

		 * Restart the TS thread to ensure the

		 * TS interrupt mode is set up again

		 * after sleep.

		 */

		ts->restart = 1;

		wake_up(&ts->irq_wait);

	}

	return 0;

}

#else

#define ucb1x00_ts_resume NULL

#endif





/*

 * Initialisation.
@@ -425,7 +404,6 @@ static void ucb1x00_ts_remove(struct ucb1x00_dev *dev) 
static struct ucb1x00_driver ucb1x00_ts_driver = {

	.add		= ucb1x00_ts_add,

	.remove		= ucb1x00_ts_remove,

	.resume		= ucb1x00_ts_resume,

};



static int __init ucb1x00_ts_init(void)

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