[PATCH] Input: only send a syn event when needed in input_dev_release_keys

[PATCH] Input: only send a syn event when needed in input_dev_release_keys

[Hans Holmberg]

A SYN event is reported in input_release_keys even if no keys are
released. Stop doing this as the superfluous event can prevent autosleep
if a user has opened a device with EPOLLWAKEUP enabled.

Based on a patch developed by Ting Li <ting.li@intel.com>.

Signed-off-by: Hans Holmberg <hans.holmberg@intel.com>
---
 drivers/input/input.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/input/input.c b/drivers/input/input.c
index 78d2499..c748805 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -675,12 +675,18 @@ EXPORT_SYMBOL(input_close_device);
 static void input_dev_release_keys(struct input_dev *dev)
 {
 	int code;
+	bool key_released = false;
 
 	if (is_event_supported(EV_KEY, dev->evbit, EV_MAX)) {
-		for_each_set_bit(code, dev->key, KEY_CNT)
+		for_each_set_bit(code, dev->key, KEY_CNT) {
 			input_pass_event(dev, EV_KEY, code, 0);
-		memset(dev->key, 0, sizeof(dev->key));
-		input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
+			key_released = true;
+		}
+
+		if (key_released) {
+			memset(dev->key, 0, sizeof(dev->key));
+			input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
+		}
 	}
 }
 
-- 
1.9.1

Re: [PATCH] Input: only send a syn event when needed in input_dev_release_keys

[Dmitry Torokhov]

Hi Hans,

On Wed, Aug 26, 2015 at 12:38 AM, Hans Holmberg <hans.holmberg@intel.com> wrote:
> A SYN event is reported in input_release_keys even if no keys are
> released. Stop doing this as the superfluous event can prevent autosleep
> if a user has opened a device with EPOLLWAKEUP enabled.
>
> Based on a patch developed by Ting Li <ting.li@intel.com>.
>
> Signed-off-by: Hans Holmberg <hans.holmberg@intel.com>

We already have a similar commit
00159f19a5057cb779146afce1cceede692af346 in next.

Thanks!

> ---
>  drivers/input/input.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/input/input.c b/drivers/input/input.c
> index 78d2499..c748805 100644
> --- a/drivers/input/input.c
> +++ b/drivers/input/input.c
> @@ -675,12 +675,18 @@ EXPORT_SYMBOL(input_close_device);
>  static void input_dev_release_keys(struct input_dev *dev)
>  {
>         int code;
> +       bool key_released = false;
>
>         if (is_event_supported(EV_KEY, dev->evbit, EV_MAX)) {
> -               for_each_set_bit(code, dev->key, KEY_CNT)
> +               for_each_set_bit(code, dev->key, KEY_CNT) {
>                         input_pass_event(dev, EV_KEY, code, 0);
> -               memset(dev->key, 0, sizeof(dev->key));
> -               input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
> +                       key_released = true;
> +               }
> +
> +               if (key_released) {
> +                       memset(dev->key, 0, sizeof(dev->key));
> +                       input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
> +               }
>         }
>  }
>
> --
> 1.9.1
>



-- 
Dmitry

RE: [PATCH] Input: only send a syn event when needed in input_dev_release_keys

[Holmberg, Hans]

Hi Dmitry,

> We already have a similar commit
> 00159f19a5057cb779146afce1cceede692af346 in next.

That'll fix the problem. I'll make sure to keep an eye on your tree & -next in the future. 
My patch doesn’t add much (it does avoid the memset when there are no bits to clear however)

Cheers!

> > ---
> >  drivers/input/input.c | 12 +++++++++---
> >  1 file changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/input/input.c b/drivers/input/input.c index
> > 78d2499..c748805 100644
> > --- a/drivers/input/input.c
> > +++ b/drivers/input/input.c
> > @@ -675,12 +675,18 @@ EXPORT_SYMBOL(input_close_device);
> >  static void input_dev_release_keys(struct input_dev *dev)  {
> >         int code;
> > +       bool key_released = false;
> >
> >         if (is_event_supported(EV_KEY, dev->evbit, EV_MAX)) {
> > -               for_each_set_bit(code, dev->key, KEY_CNT)
> > +               for_each_set_bit(code, dev->key, KEY_CNT) {
> >                         input_pass_event(dev, EV_KEY, code, 0);
> > -               memset(dev->key, 0, sizeof(dev->key));
> > -               input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
> > +                       key_released = true;
> > +               }
> > +
> > +               if (key_released) {
> > +                       memset(dev->key, 0, sizeof(dev->key));
> > +                       input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
> > +               }
> >         }
> >  }
> >
> > --
> > 1.9.1
> >
> 
> 
> 
> --
> Dmitry