On Tue, Mar 01, 2011 at 04:54:19PM +0000, Mark Brown wrote: > 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. > > 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. > Hmm, this is quite ugly. The race that you mentioned should be dealt with by rearranging the order in which you disable IRQ and enable the conversions. I.e. in wm831x_ts_pen_down_irq() you should do: disable_irq_nosync(wm831x_ts->pd_irq); wm831x_ts->pendown = true; ... enable_irq(wm831x_ts->data_irq); The issue is that wm831x_ts_input_close() is racy; it simply writes into WM831X_TOUCH_CONTROL_1 and hopes that it will stick... What is needed I guess is wm831x_ts->open flag that wm831x_ts_input_open() would set and wm831x_ts_input_close() would reset and the interrupt handlers would check before touching the registers or enabling their counterparts. wm831x_ts_input_close() would reset the flag first and then disable first pd_irq and then data_irq, before writing to the control register. The only issue is to keep track of irq disble counters. The issue with enable_irq() not working in the irq handler thread should be dealt at the controller level (i.e. fix it so that it works). Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
