On Tue, Aug 14, 2012 at 01:50:38PM -0700, Ping Cheng wrote: > On Tue, Aug 14, 2012 at 12:53 PM, Dmitry Torokhov > <dmitry.torokhov@xxxxxxxxx> wrote: > > On Tuesday, August 14, 2012 12:32:21 PM Ping Cheng wrote: > >> On Sun, Aug 12, 2012 at 2:42 PM, Henrik Rydberg <rydberg@xxxxxxxxxxx> wrote: > >> > Many MT devices send a number of keys along with the mt information. > >> > This patch makes sure that there is room for them in the packet > >> > buffer. > >> > > >> > Signed-off-by: Henrik Rydberg <rydberg@xxxxxxxxxxx> > >> > --- > >> > > >> > drivers/input/input.c | 10 +++++++--- > >> > 1 file changed, 7 insertions(+), 3 deletions(-) > >> > > >> > diff --git a/drivers/input/input.c b/drivers/input/input.c > >> > index 6e90705..8ebf116 100644 > >> > --- a/drivers/input/input.c > >> > +++ b/drivers/input/input.c > >> > @@ -1777,6 +1777,9 @@ static unsigned int > >> > input_estimate_events_per_packet(struct input_dev *dev)> > >> > if (test_bit(i, dev->relbit)) > >> > > >> > events++; > >> > > >> > + /* Make room for KEY and MSC events */ > >> > + events += 7; > >> > >> Hi Henrik, > >> > >> It is nice to get rid of the redundant pieces and to incorporate > >> common functions. Thank you. > >> > >> I have a question about the code above though. Why do we use 7 > >> instead of going through the keys like: > >> > >> for (i = 0; i < KEY_MAX; i++) > >> if (test_bit(i, dev->keybit)) > >> events++; > > > > Because that would result in gross over-estimation for many devices - > > my keyboard has 100+ keys but it never sends all of them in one event > > frame, not even if I can get a cat to lay on it ;) > > Thanks for the prompt reply. I thought you were on vacation ;-). No, just generally busy ;( > > So, what device are we talking about here? I thought it is a touch > device with a few extra buttons, which are reported as key events. Am > I missing something? I was talking about a bog-standard computer keyboard here. > > If it is a touch device, we won't have too many buttons. So, > test_bit(i, dev->keybit) won't be true for more than the number of > buttons that declared by __set_bit(). input_estimate_events_per_packet() is a generic routine that is used for all devices, not only [multi]touch. > > I would think we could play a keyboard (this keyboard does not have > letters on it ;-) with ten fingers. But even that keyboard would have more than 10 keys, right? So even though max_events should be 10 + 10 + 1 (10 keys, 10 msc, syn) your loop would produce what 88 + 88 + 1 for full size music keyboard? 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
