Re: [PATCH 09/19] Input: MT - Handle frame synchronization in core

On Thu, Aug 16, 2012 at 11:07 AM, Henrik Rydberg [off-list ref] wrote:

On Wed, Aug 15, 2012 at 04:28:17PM -0700, Ping Cheng wrote:

quoted

On Sun, Aug 12, 2012 at 2:42 PM, Henrik Rydberg [off-list ref] wrote:

quoted

Collect common frame synchronization tasks in a new function,
input_mt_sync_frame(). Depending on the flags set, it drops
unseen contacts and performs pointer emulation.

Signed-off-by: Henrik Rydberg <redacted>

I went through the patchset except those for bcm5974. Since there are
changes that affect other drivers, do you plan to update the affected
drivers as well?

I am not sure what you mean here? There is a patch with in-kernel api
changes, which also changes all drivers using the api. Some of those
drivers will benefit from further changes, but that is a different
story.

I meant that some new routines require individual MT drivers to be
updated to adapt to the new implementation.

For example, the new input_mt_init_slots() takes care of the
__set_bit() functions in one place. That is great. But, it requires
wacom_wac.c to be updated since it has an interface change. I guess
there are other drivers calling input_mt_init_slots as well.

I was wondering if you plan to update all drivers after this patchset
is accepted or if you need us to chime in.

quoted

quoted

+void input_mt_sync_frame(struct input_dev *dev)
+{
+       struct input_mt *mt = dev->mt;
+       struct input_mt_slot *s;
+
+       if (!mt)
+               return;
+
+       if (mt->flags & INPUT_MT_DROP_UNUSED) {
+               for (s = mt->slots; s != mt->slots + mt->num_slots; s++) {
+                       if (s->frame == mt->frame)
+                               continue;
+                       input_mt_slot(dev, s - mt->slots);
+                       input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
+               }
+       }
+
+       if (mt->flags & INPUT_MT_POINTER)
+               input_mt_report_pointer_emulation(dev, true);
+
+       if (mt->flags & INPUT_MT_DIRECT)
+               input_mt_report_pointer_emulation(dev, false);
+
+       mt->frame++;

Where do we reset this frame counter?

Why would we reset it? It is used in the core to keep track of changes
per frame, and may wrap around without issues.

From what I see, frame/mt is only initialized when driver starts.

Frame will be increased by MT events while the driver running. If this
is true, won't it be possible the value gets too large?

I might have missed a detail about frame somewhere in the patchset.

Ping