Re: [PATCH] input: Add a detailed multi-touch finger data report protocol

Dmitry Torokhov
2008-11-19T16:37:24Z

Hi Henrik,

On Fri, Nov 07, 2008 at 12:15:29PM +0100, Henrik Rydberg wrote:
> In order to utilize the full power of the new multi-touch devices, a
> way to report detailed finger data to user space is needed. This patch
> adds a multi-touch (MT) protocol which allows drivers to report details
> for an arbitrary number of fingers.
>
> BTN_MT_REPORT_PACKET
>
> The driver presses this button to indicate the start of a packet of
> finger data. The button is released after the whole packet has been
> reported.
>
> BTN_MT_REPORT_FINGER
>
> The driver presses this button to indicate the start of a new
> finger. The button is released when the finger has been reported.
>
> In order to stay compatible with existing applications, the data
> reported in a finger packet must not be recognized as single-touch
> events. Therefore, a specific set of ABS_MT events is used instead.
>
> Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
> ---
> include/linux/input.h | 12 ++++++++++++
> 1 files changed, 12 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/input.h b/include/linux/input.h
> index b86fb55..c82dd42 100644
> --- a/include/linux/input.h
> +++ b/include/linux/input.h
> @@ -590,6 +590,9 @@ struct input_absinfo {
> #define KEY_NUMERIC_STAR 0x20a
> #define KEY_NUMERIC_POUND 0x20b
>
> +#define BTN_MT_REPORT_PACKET 0x210 /* report multitouch packet data */
> +#define BTN_MT_REPORT_FINGER 0x211 /* report multitouch finger data */
> +
> /* We avoid low common keys in module aliases so they don't get huge. */
> #define KEY_MIN_INTERESTING KEY_MUTE
> #define KEY_MAX 0x2ff
> @@ -642,6 +645,15 @@ struct input_absinfo {
> #define ABS_TOOL_WIDTH 0x1c
> #define ABS_VOLUME 0x20
> #define ABS_MISC 0x28
> +#define ABS_MT_TOUCH 0x30 /* Diameter of touching circle */
> +#define ABS_MT_TOUCH_MAJOR 0x30 /* Major axis of touching ellipse */
> +#define ABS_MT_TOUCH_MINOR 0x31 /* Minor axis of touching ellipse */
> +#define ABS_MT_WIDTH 0x32 /* Diameter of approaching circle */
> +#define ABS_MT_WIDTH_MAJOR 0x32 /* Major axis of approaching ellipse */
> +#define ABS_MT_WIDTH_MINOR 0x33 /* Minor axis of approaching ellipse */
> +#define ABS_MT_ORIENTATION 0x34 /* Ellipse orientation */
> +#define ABS_MT_POSITION_X 0x35 /* Center X ellipse position */
> +#define ABS_MT_POSITION_Y 0x36 /* Center Y ellipse position */
> #define ABS_MAX 0x3f
> #define ABS_CNT (ABS_MAX+1)
>

Sorry for the long silence. I don't think utilizing button events for
this is a good idea. I'd rather just start reporting extended touch
events for a finger and signal end of sub-packet with something like
EV_SYN/SYN_MT_REPORT.

--
Dmitry