Hi Henrik


On 2019/09/18 3:25, Henrik Rydberg wrote:

Hi Jiada,

quoted

input_mt_report_slot_state() ignores the tool when the slot is closed.
which has caused a bit of confusion.
This patch introduces input_mt_report_slot_inactive() to report slot
inactive state.
replaces all input_mt_report_slot_state() with
input_mt_report_slot_inactive() in case of close of slot.

This patch looks very odd, I am afraid.

When a driver needs to use input_mt functions, it first calls 
input_mt_init_slots() during setup. The MT state then remains in effect 
until the driver is destroyed. Thus, there is no valid case when 
input_mt_report_slot_state() would fail to execute the line

    input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1)

when active == false.

What input_mt_report_slot_state() does do, however, is to ignore the 
event when no MT state has been set, which does happen for some drivers 
handling both normal and MT devices. Changing such a driver in the way 
you suggest would introduce new events in existing, working cases, and 
possibly break userspace. We should try very hard to avoid it.

thanks for your comment,

Just to make sure, I think your comment is for
patch "[PATCH v3 01/49] Input: switch to use return value of 
input_mt_report_slot_state"
not for "[PATCH v3 02/49] Input: introduce 
input_mt_report_slot_inactive", right?

yes, I agree
by having change:

-    input_mt_report_slot_state(dev, tool_type, active);
-    if (active) {
+        if (input_mt_report_slot_state(dev, tool_type, active)){
              ... ...
      }

the logic of the driver is changed, when (mt == NULL && active == true).
I will drop patch "Input: switch to use return value of" in next version

Thanks,
Jiada

Thanks,

Henrik