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[2/2] Input: wm831x-ts - Fix races with IRQ management

Message ID 1300142701-22260-2-git-send-email-broonie@opensource.wolfsonmicro.com (mailing list archive)
State New, archived
Headers show

Commit Message

Mark Brown March 14, 2011, 10:45 p.m. UTC
None
diff mbox

Patch

diff --git a/drivers/input/touchscreen/wm831x-ts.c b/drivers/input/touchscreen/wm831x-ts.c
index 6ae054f..3f825cb 100644
--- a/drivers/input/touchscreen/wm831x-ts.c
+++ b/drivers/input/touchscreen/wm831x-ts.c
@@ -68,8 +68,29 @@  struct wm831x_ts {
 	unsigned int pd_irq;
 	bool pressure;
 	bool pen_down;
+	struct work_struct pd_data_work;
+	struct work_struct data_pd_work;
 };
 
+static void wm831x_pd_data(struct work_struct *work)
+{
+	struct wm831x_ts *wm831x_ts =
+		container_of(work, struct wm831x_ts, pd_data_work);
+
+	disable_irq(wm831x_ts->pd_irq);
+	enable_irq(wm831x_ts->data_irq);
+	dev_dbg(wm831x_ts->wm831x->dev, "IRQ PD->DATA done\n");
+}
+
+static void wm831x_data_pd(struct work_struct *work)
+{
+	struct wm831x_ts *wm831x_ts =
+		container_of(work, struct wm831x_ts, data_pd_work);
+
+	enable_irq(wm831x_ts->pd_irq);
+	dev_dbg(wm831x_ts->wm831x->dev, "IRQ DATA->PD done\n");
+}
+
 static irqreturn_t wm831x_ts_data_irq(int irq, void *irq_data)
 {
 	struct wm831x_ts *wm831x_ts = irq_data;
@@ -110,7 +131,10 @@  static irqreturn_t wm831x_ts_data_irq(int irq, void *irq_data)
 	}
 
 	if (!wm831x_ts->pen_down) {
+		/* Switch from data to pen down */
+		dev_dbg(wm831x->dev, "IRQ DATA->PD\n");
 		disable_irq_nosync(wm831x_ts->data_irq);
+		schedule_work(&wm831x_ts->data_pd_work);
 
 		/* Don't need data any more */
 		wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_1,
@@ -156,7 +180,10 @@  static irqreturn_t wm831x_ts_pen_down_irq(int irq, void *irq_data)
 			WM831X_TCHPD_EINT, WM831X_TCHPD_EINT);
 
 	wm831x_ts->pen_down = true;
-	enable_irq(wm831x_ts->data_irq);
+
+	/* Switch from pen down to data */
+	dev_dbg(wm831x->dev, "IRQ PD->DATA\n");
+	schedule_work(&wm831x_ts->pd_data_work);
 
 	return IRQ_HANDLED;
 }
@@ -182,13 +209,36 @@  static void wm831x_ts_input_close(struct input_dev *idev)
 	struct wm831x_ts *wm831x_ts = input_get_drvdata(idev);
 	struct wm831x *wm831x = wm831x_ts->wm831x;
 
+	/* Shut the controller down, disabling all other functionality */
+	wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_1,
+			WM831X_TCH_ENA, 0);
+
+	/* Make sure any pending IRQs are done, the above will prevent
+	 * new ones firing.
+	 */
+	synchronize_irq(wm831x_ts->data_irq);
+	synchronize_irq(wm831x_ts->pd_irq);
+
+	/* Make sure the IRQ completion work is quiesced */
+	flush_work_sync(&wm831x_ts->data_pd_work);
+	flush_work_sync(&wm831x_ts->pd_data_work);
+
+	/* If we ended up with the pen down then make sure we revert back
+	 * to pen detection state for the next time we start up.
+	 */
+	if (wm831x_ts->pen_down) {
+		disable_irq(wm831x_ts->data_irq);
+		enable_irq(wm831x_ts->pd_irq);
+		wm831x_ts->pen_down = false;
+	}
+
+	/* Be nice to the next user and make sure everything is
+	 * flagged as disabled.
+	 */
 	wm831x_set_bits(wm831x, WM831X_TOUCH_CONTROL_1,
 			WM831X_TCH_ENA | WM831X_TCH_CVT_ENA |
 			WM831X_TCH_X_ENA | WM831X_TCH_Y_ENA |
 			WM831X_TCH_Z_ENA, 0);
-
-	if (wm831x_ts->pen_down)
-		disable_irq(wm831x_ts->data_irq);
 }
 
 static __devinit int wm831x_ts_probe(struct platform_device *pdev)
@@ -212,6 +262,8 @@  static __devinit int wm831x_ts_probe(struct platform_device *pdev)
 
 	wm831x_ts->wm831x = wm831x;
 	wm831x_ts->input_dev = input_dev;
+	INIT_WORK(&wm831x_ts->pd_data_work, wm831x_pd_data);
+	INIT_WORK(&wm831x_ts->data_pd_work, wm831x_data_pd);
 
 	/*
 	 * If we have a direct IRQ use it, otherwise use the interrupt