Messages in this thread | | | Date | Sat, 3 Feb 2018 11:35:04 -0800 | From | Dmitry Torokhov <> | Subject | Re: [PATCH v2] Input: matrix_keypad - fix keypad does not response |
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Hi Zhang,
On Sat, Feb 03, 2018 at 11:58:16PM +0800, Zhang Bo wrote: > If matrix_keypad_stop() is calling and the keypad interrupt is triggered, > disable_row_irqs() is called by both matrix_keypad_interrupt() and > matrix_keypad_stop() at the same time. then disable_row_irqs() is called > twice, and the device enter suspend state before keypad->work is executed. > At this condition the device will start keypad and enable irq once after > resume. and then irqs are disabled yet because irqs are disabled twice and > only enable once. > > Take lock around keypad->stopped and queue delayed work in > matrix_keypad_start() and matrix_keypad_stop() to ensure irqs operation and > scheduling scan work are in atomic operation. > > Signed-off-by: Zhang Bo <zbsdta@126.com> > --- > Changes in v2: > - Change commit message and full name in the signed-off-by tag. > > drivers/input/keyboard/matrix_keypad.c | 18 ++++++++++++------ > 1 file changed, 12 insertions(+), 6 deletions(-) > > diff --git a/drivers/input/keyboard/matrix_keypad.c b/drivers/input/keyboard/matrix_keypad.c > index 1f316d66e6f7..13fe51824637 100644 > --- a/drivers/input/keyboard/matrix_keypad.c > +++ b/drivers/input/keyboard/matrix_keypad.c > @@ -169,7 +169,8 @@ static void matrix_keypad_scan(struct work_struct *work) > /* Enable IRQs again */ > spin_lock_irq(&keypad->lock); > keypad->scan_pending = false; > - enable_row_irqs(keypad); > + if (keypad->stopped == false) > + enable_row_irqs(keypad); > spin_unlock_irq(&keypad->lock); > } > > @@ -202,14 +203,16 @@ static int matrix_keypad_start(struct input_dev *dev) > { > struct matrix_keypad *keypad = input_get_drvdata(dev); > > + spin_lock_irq(&keypad->lock); > keypad->stopped = false; > - mb(); > > /* > * Schedule an immediate key scan to capture current key state; > * columns will be activated and IRQs be enabled after the scan. > */ > - schedule_delayed_work(&keypad->work, 0); > + if (keypad->scan_pending == false)
How can we have the pending scan if the keypad was disabled.
> + schedule_delayed_work(&keypad->work, 0); > + spin_unlock_irq(&keypad->lock);
I do not think the change to matrix_keypad_start() is needed. If device is quiesced we do not have issue of ISR racing with us here.
> > return 0; > } > @@ -218,14 +221,17 @@ static void matrix_keypad_stop(struct input_dev *dev) > { > struct matrix_keypad *keypad = input_get_drvdata(dev); > > + spin_lock_irq(&keypad->lock); > keypad->stopped = true; > - mb(); > - flush_work(&keypad->work.work); > /* > * matrix_keypad_scan() will leave IRQs enabled; > * we should disable them now. > */ > - disable_row_irqs(keypad); > + if (keypad->scan_pending == false) > + disable_row_irqs(keypad); > + spin_unlock_irq(&keypad->lock); > + > + flush_work(&keypad->work.work);
This is wrong, you should not have moved the flush_work() here. The logic is as follows:
- set the "stopped" flag - ensure that ISR has completed - ensure that work item has finished (by doing flush_work()) - this will make sure that interrupts are enabled (either ISR noticed "stopped flag" and did not touch them, or ISR scheduled work and work item re-enabled them) - finally disable IRQs
Your change breaks this.
As far as I can see, the only change that is needed is this at the beginning of matrix_keypad_stop():
spin_lock_irq(&keypad->lock); keypad->stopped = true; spin_unlock_irq(&keypad->lock);
Thanks.
-- Dmitry
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