On Tue, 2018-03-13 at 11:09 -0700, Dmitry Torokhov wrote: > On Mon, Mar 12, 2018 at 10:51:48PM +0000, Ben Hutchings wrote: > > matrix_keypad_stop() now serialises with matrix_keypad_interrupt() > > using spin_lock_irq() while setting the "stopped" flag, but it drops > > the lock before disabling the interrupt sources. If an interrupt is > > asserted at this point, matrix_keypad_interrupt() will ignore it > > because stopped is true. The interrupt will remain asserted and it > > may be called repeatedly, potentially leading to a hard lockup on a UP > > system. > > No, it will not. We acknowledge interrupt (return IRQ_HANDLED) even when > keypad is stopped, and because we are dealing with a bunch of GPIOs (and > not some controller that has internal state and would not deassert the > attention line until we read or otherwise clear the state) the > interrupts will not be re-assered (unless there is a keypress, but even > then we'll simply re-acknowledge interrupt again). [...] Returning IRQ_HANDLED has no effect on the hardware; it's mostly used for spurious interrupt detection. But I think what you're saying that these interrupts will always be edge-triggered, not level-triggered - is that right? In which case I agree that screaming interrupts won't be a problem. Ben. -- Ben Hutchings Software Developer, Codethink Ltd. -- 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
