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Commit 29cc309d authored by Nicolas Boichat's avatar Nicolas Boichat Committed by Jiri Kosina
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HID: hid-multitouch: forward MSC_TIMESTAMP 



Computes and forwards the device timestamp according to the specification.

Many devices use a 16-bit timestamp field, with a resolution of 100us,
therefore rolling around very frequently (every 6.5 seconds). To make sure
there is no ambiguity, the timestamp reported to the input stack reset to
0 whenever the time between 2 received events is greater than
MAX_TIMESTAMP_INTERVAL (1 second).

Signed-off-by: default avatarNicolas Boichat <drinkcat@chromium.org>
Acked-by: default avatarBenjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent b42a362e

drivers/hid/hid-multitouch.c

+42 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ 
#include <linux/module.h>

#include <linux/slab.h>

#include <linux/input/mt.h>

#include <linux/jiffies.h>

#include <linux/string.h>

#include <linux/timer.h>
@@ -136,6 +137,9 @@ struct mt_device { 
	bool serial_maybe;	/* need to check for serial protocol */

	bool curvalid;		/* is the current contact valid? */

	unsigned mt_flags;	/* flags to pass to input-mt */

	__s32 dev_time;		/* the scan time provided by the device */

	unsigned long jiffies;	/* the frame's jiffies */

	int timestamp;		/* the timestamp to be sent */

};



static void mt_post_parse_default_settings(struct mt_device *td);
@@ -177,6 +181,12 @@ static void mt_post_parse(struct mt_device *td); 
#define MT_DEFAULT_MAXCONTACT	10

#define MT_MAX_MAXCONTACT	250



/*

 * Resync device and local timestamps after that many microseconds without

 * receiving data.

 */

#define MAX_TIMESTAMP_INTERVAL	1000000



#define MT_USB_DEVICE(v, p)	HID_DEVICE(BUS_USB, HID_GROUP_MULTITOUCH, v, p)

#define MT_BT_DEVICE(v, p)	HID_DEVICE(BUS_BLUETOOTH, HID_GROUP_MULTITOUCH, v, p)
@@ -583,6 +593,12 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi, 
				cls->sn_pressure);

			mt_store_field(usage, td, hi);

			return 1;

		case HID_DG_SCANTIME:

			hid_map_usage(hi, usage, bit, max,

				EV_MSC, MSC_TIMESTAMP);

			input_set_capability(hi->input, EV_MSC, MSC_TIMESTAMP);

			mt_store_field(usage, td, hi);

			return 1;

		case HID_DG_CONTACTCOUNT:

			/* Ignore if indexes are out of bounds. */

			if (field->index >= field->report->maxfield ||
@@ -718,6 +734,7 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input) 
static void mt_sync_frame(struct mt_device *td, struct input_dev *input)

{

	input_mt_sync_frame(input);

	input_event(input, EV_MSC, MSC_TIMESTAMP, td->timestamp);

	input_sync(input);

	td->num_received = 0;

	if (test_bit(MT_IO_FLAGS_ACTIVE_SLOTS, &td->mt_io_flags))
@@ -727,6 +744,28 @@ static void mt_sync_frame(struct mt_device *td, struct input_dev *input) 
	clear_bit(MT_IO_FLAGS_ACTIVE_SLOTS, &td->mt_io_flags);

}



static int mt_compute_timestamp(struct mt_device *td, struct hid_field *field,

		__s32 value)

{

	long delta = value - td->dev_time;

	unsigned long jdelta = jiffies_to_usecs(jiffies - td->jiffies);



	td->jiffies = jiffies;

	td->dev_time = value;



	if (delta < 0)

		delta += field->logical_maximum;



	/* HID_DG_SCANTIME is expressed in 100us, we want it in us. */

	delta *= 100;



	if (jdelta > MAX_TIMESTAMP_INTERVAL)

		/* No data received for a while, resync the timestamp. */

		return 0;

	else

		return td->timestamp + delta;

}



static int mt_touch_event(struct hid_device *hid, struct hid_field *field,

				struct hid_usage *usage, __s32 value)

{
@@ -787,6 +826,9 @@ static void mt_process_mt_event(struct hid_device *hid, struct hid_field *field, 
		case HID_DG_HEIGHT:

			td->curdata.h = value;

			break;

		case HID_DG_SCANTIME:

			td->timestamp = mt_compute_timestamp(td, field, value);

			break;

		case HID_DG_CONTACTCOUNT:

			break;

		case HID_DG_TOUCH:

include/linux/hid.h

+1 −0
Original line number Diff line number Diff line
@@ -289,6 +289,7 @@ struct hid_item { 
#define HID_DG_DEVICEINDEX	0x000d0053

#define HID_DG_CONTACTCOUNT	0x000d0054

#define HID_DG_CONTACTMAX	0x000d0055

#define HID_DG_SCANTIME		0x000d0056

#define HID_DG_BUTTONTYPE	0x000d0059

#define HID_DG_BARRELSWITCH2	0x000d005a

#define HID_DG_TOOLSERIALNUMBER	0x000d005b