Re: [PATCH 02/19] Input: Improve the events-per-packet estimate

On Tue, Aug 14, 2012 at 1:01 PM, Henrik Rydberg [off-list ref] wrote:

Hi Ping,

Long time no see. :-)

quoted

quoted

+       /* Make room for KEY and MSC events */
+       events += 7;

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++;

Keyboards register a large amount of different keys, but seldom send
more than one or two at a time. The value 7 is ad hoc, admittedly, but
it makes the default buffer 8 bytes, which happens to precisely match
the default buffer in evdev.

That can be a valid reason until we need to report more keys
simultaneously. Please update the comments so we know why we end up
with 7.

Thank you.

Ping