Re: [PATCH 1/2] input: mt: Introduce MT event slots (rev 5)

From: Chase Douglas
Date: Thu Jun 10 2010 - 10:15:35 EST

On Sun, 2010-05-23 at 00:30 +0200, Henrik Rydberg wrote:
> With the rapidly increasing number of intelligent multi-contact and
> multi-user devices, the need to send digested, filtered information
> from a set of different sources within the same device is imminent.
> This patch adds the concept of slots to the MT protocol. The slots
> enumerate a set of identified sources, such that all MT events
> can be passed independently and selectively per identified source.
> The protocol works like this: Instead of sending a SYN_MT_REPORT
> event immediately after the contact data, one sends an ABS_MT_SLOT
> event immediately before the contact data. The input core will only
> emit events for slots with modified MT events. It is assumed that
> the same slot is used for the duration of an initiated contact.
> Signed-off-by: Henrik Rydberg <rydberg@xxxxxxxxxxx>
> ---
> Revision 5 incorporates the following changes:
> - Rename the slot event to ABS_MT_SLOT to keep all MT-related events
> in the same namespace.
> - Move the MT slot event list to input.h so that it can be read
> by userspace.
> drivers/input/input.c | 105 +++++++++++++++++++++++++++++++++++++------------
> include/linux/input.h | 44 ++++++++++++++++++++
> 2 files changed, 123 insertions(+), 26 deletions(-)

I was wondering what the status of this patch was. I reviewed it and I
think it's a good improvement of the protocol. I think it will help
simplify things in userspace event handling, and should reduce the noise
in evdev. I also like the incremental approach in that it doesn't force
drivers into the new protocol, but makes it available for them when they
can use it.

Acked-by: Chase Douglas <chase.douglas@xxxxxxxxxxxxx>

Long term, I think it makes the most sense to have a layer inside the
kernel to do software touch tracking and expose all MT data through the
slots protocol instead of it being determined by the capabilities of the

-- Chase

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