Re: [PATCH 4/5] input: wacom: Add support for the Bamboo Touch trackpad (rev4)

[Ping Cheng <pinglinux@gmail.com>]

On Wed, Oct 13, 2010 at 11:21 AM, Henrik Rydberg <rydberg@euromail.se> wrote:
>
> In the language of ABS_MT, there is a distinction between slot and id. The slot
> is the handle used to communicate a unique touch. The id is the identifier of
> that touch. The device tells us how many slots we have. The range of ids is in
> principle infinite. In practice, it is set to a large number.
>
> To answer a possible follow-up question: from the tracking id, you can tell if a
> contact is present, if it is new, and if it is older than another contact.

I see. Somehow I remember tracking ID is the ID from the hardware/firmware.

>>> +
>>> +       input_report_key(input, BTN_LEFT, (data[1] & 0x08) != 0);
>>> +       input_report_key(input, BTN_FORWARD, (data[1] & 0x04) != 0);
>>> +       input_report_key(input, BTN_BACK, (data[1] & 0x02) != 0);
>>> +       input_report_key(input, BTN_RIGHT, (data[1] & 0x01) != 0);
>>
>> This implementation impairs the value of those buttons since I know a
>> lot of users want them configurable. If we can not or do not pass a
>> generic set to the userland, we will need to make it configurable in
>> the kernel driver as Dmitry suggested (if I remember it correctly).
>> Which approach, in the userland or the kernel, do you like, Henrik?
>
> Perhaps I should not remind you that the current code was your suggestion. ;-)

Yes, I remember that. TBH, I did not want to open another can of worms
then. And I did not have time to care about where that train went :).

> In my mind, these are buttons just like the buttons on any mouse or trackpad.

For this particular model, it might be fine. My concern is for the other models.

> Regarding remapping, I think it matters if buttons have strong or weak semantics.

Supporting button remapping is not a question. It is a decision. The
question is how. I hate to open this can of worms even now. But, we do
have to face the reality.

Currently, I use BTN_TOOL_FINGER to group those buttons together and
to pass them to the userland. This has never been an issue before MT
became such a hot topic. Now, we need to EITHER choose a new
BTN_TOOL_something to pass the poor buttons to the userland OR use the
kernel approach that Dmitry suggested. I am open to all suggestions
although I feel passing the buttons to the userland is a
better/cleaner solution.

My goal is to get a consensus so no one can blame me or the maintainer
for the decision :). Fair?

Ping
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