From: Mark Brown Date: Thu, 28 Apr 2011 06:08:34 +0000 (-0700) Subject: Input: wm831x-ts - fix races with IRQ management X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=f5346668150c37094b42cc2d07ec5fd1451eb980;p=linux-beck.git Input: wm831x-ts - fix races with IRQ management If the WM831x pen down and data IRQs run in parallel it is possible for the data and pen down IRQs to deadlock themselves as one is part way through disabling its operation while the other is part way through enabling. Fix this by always disabling the pen down interrupt while data is active and vice versa. When a changeover is required we disable the IRQ that is to be stopped then schedule work that will enable the new IRQ. We need to handle the data flow in the data IRQ as the readback from the device needs to be ordered correctly with the IRQ for robust operation. This also fixes an issue when using the built in IRQs due to enable_irq() not being valid from interrupt context on an interrupt controller with bus operations like the built in IRQ controller - this issue may also have affected other interrupt controllers. We can't rely on having the data and pen down IRQs available via GPIOs on the CPU on every system. Signed-off-by: Mark Brown Signed-off-by: Dmitry Torokhov --- diff --git a/drivers/input/touchscreen/wm831x-ts.c b/drivers/input/touchscreen/wm831x-ts.c index 6ae054f8e0aa..b9373012b3e6 100644 --- a/drivers/input/touchscreen/wm831x-ts.c +++ b/drivers/input/touchscreen/wm831x-ts.c @@ -68,8 +68,23 @@ struct wm831x_ts { unsigned int pd_irq; bool pressure; bool pen_down; + struct work_struct pd_data_work; }; +static void wm831x_pd_data_work(struct work_struct *work) +{ + struct wm831x_ts *wm831x_ts = + container_of(work, struct wm831x_ts, pd_data_work); + + if (wm831x_ts->pen_down) { + enable_irq(wm831x_ts->data_irq); + dev_dbg(wm831x_ts->wm831x->dev, "IRQ PD->DATA done\n"); + } else { + 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; @@ -110,6 +125,9 @@ 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); /* Don't need data any more */ @@ -128,6 +146,8 @@ static irqreturn_t wm831x_ts_data_irq(int irq, void *irq_data) ABS_PRESSURE, 0); input_report_key(wm831x_ts->input_dev, BTN_TOUCH, 0); + + schedule_work(&wm831x_ts->pd_data_work); } input_sync(wm831x_ts->input_dev); @@ -141,6 +161,11 @@ static irqreturn_t wm831x_ts_pen_down_irq(int irq, void *irq_data) struct wm831x *wm831x = wm831x_ts->wm831x; int ena = 0; + if (wm831x_ts->pen_down) + return IRQ_HANDLED; + + disable_irq_nosync(wm831x_ts->pd_irq); + /* Start collecting data */ if (wm831x_ts->pressure) ena |= WM831X_TCH_Z_ENA; @@ -156,7 +181,10 @@ 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 +210,28 @@ 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 too */ 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); + WM831X_TCH_ENA | WM831X_TCH_X_ENA | + WM831X_TCH_Y_ENA | WM831X_TCH_Z_ENA, 0); - if (wm831x_ts->pen_down) + /* 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->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; + } } static __devinit int wm831x_ts_probe(struct platform_device *pdev) @@ -212,6 +255,7 @@ 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_work); /* * If we have a direct IRQ use it, otherwise use the interrupt