linux-kernel - Re: [PATCH 2/2] input: mt: Document the MT event slot protocol (rev2)

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Message-ID: <AANLkTin9ahtqL7jrUP4C0zF9-P3rUg7ktN93-hcqdDnj@mail.gmail.com>
Date:	Mon, 24 May 2010 10:06:15 -0700
From:	Ping Cheng <pinglinux@...il.com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Peter Hutterer <peter.hutterer@...-t.net>,
	Henrik Rydberg <rydberg@...omail.se>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	Mika Kuoppala <mika.kuoppala@...ia.com>,
	Benjamin Tissoires <tissoire@...a.fr>,
	Stephane Chatty <chatty@...c.fr>,
	Rafi Rubin <rafi@...s.upenn.edu>,
	Michael Poole <mdpoole@...ilus.org>
Subject: Re: [PATCH 2/2] input: mt: Document the MT event slot protocol (rev2)

On Mon, May 24, 2010 at 8:59 AM, Dmitry Torokhov
<dmitry.torokhov@...il.com> wrote:
> On Sun, May 23, 2010 at 11:07:27PM -0700, Ping Cheng wrote:
>> On Sun, May 23, 2010 at 9:58 PM, Peter Hutterer
>> <peter.hutterer@...-t.net> wrote:
>> >> > And yes, you could add it once we find it's an issue, but by then someone
>> >> > has already spent time to work around this. And when you then start sending
>> >> > slot events all the time, you admit that writing the workaround was just a
>> >> > time waster :)
>> >>
>> >> Work around what, exactly?
>> >
>> > I was referring to having a protocol where processes has to ignore contacts
>> > already down until they've been there when a contact was pressed (and your
>> > comment that if this becomes an issue it could be added lateron).
>> > Now, the ignoring part needs to be written (this is the "workaround"
>> > referred to above). if you're planning to add it later, we need to cater for
>> > that part as well then, having two implementations depending on the kernel
>> > versions.
>> >
>> > but this is just for clarification, it's a moot point anyway given that
>> > button events have the same behaviour.
>>
>> This topic is outside of the _MT_ protocol discussion.
>>
>> However, it is indeed an issue with all filtered input events, both
>> for MT and regular ones.
>>
>> I think we need to add an ioctl to enable user land driver/client to
>> signal the kernel driver to send all events without filtering, just
>> once. Hot-plugged devices and X driver starts after user has contacted
>> with the device are two examples that the client would miss filtered
>> events.
>>
>> Dmitry, do you think it is a valid suggestion?
>>
>
> What about using EVIOCGKEY/EVIOCGSW/EVIOCGABS?

Those EVIOCs only give us the static values (max/min/supported keys,
etc.).  We need their dynamic input data here, the actual x, y,
button, pressure, etc. Am I missing something about those EVIOs?

Ping
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