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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: Nicolas Boichat <drinkcat@chromium.org>
Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Nicolas Boichat 2017-08-22 09:10:11 +08:00 committed by Jiri Kosina
parent b42a362e6d
commit 29cc309d8b
2 changed files with 43 additions and 0 deletions
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42
drivers/hid/hid-multitouch.c
View File

@ -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:

1
include/linux/hid.h
View File

@ -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