Computes the scan time according to the specification.
It also ensures that if the time between two events is greater
than MAX_SCAN_INTERVAL, the scan time will be reset.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxx>
---
drivers/hid/hid-multitouch.c | 45 ++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 43 insertions(+), 2 deletions(-)
diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 1f3d1e0..5902567 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -32,6 +32,7 @@
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/input/mt.h>
+#include <linux/jiffies.h>
#include "usbhid/usbhid.h"
@@ -98,6 +99,9 @@ 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 */
+ unsigned scan_time; /* the scan time to be sent */
};
/* classes of device behavior */
@@ -126,6 +130,9 @@ struct mt_device {
#define MT_DEFAULT_MAXCONTACT 10
#define MT_MAX_MAXCONTACT 250
+#define MAX_SCAN_TIME INT_MAX
+#define MAX_SCAN_INTERVAL 500000
+
#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)
@@ -451,12 +458,20 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
mt_store_field(usage, td, hi);
td->last_field_index = field->index;
return 1;
+ case HID_DG_SCANTIME:
+ hid_map_usage(hi, usage, bit, max,
+ EV_ABS, ABS_SCAN_TIME);
+ input_set_abs_params(hi->input,
+ ABS_SCAN_TIME, 0, MAX_SCAN_TIME, 0, 0);
+ td->last_field_index = field->index;
+ return 1;
case HID_DG_CONTACTCOUNT:
td->last_field_index = field->index;
return 1;
case HID_DG_CONTACTMAX:
- /* we don't set td->last_slot_field as contactcount and
- * contact max are global to the report */
+ /* we don't set td->last_slot_field as scan time,
+ * contactcount and contact max are global to the
+ * report */
td->last_field_index = field->index;
return -1;
}
@@ -565,11 +580,34 @@ 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_event(input, EV_ABS, ABS_SCAN_TIME, td->scan_time);
input_mt_sync_frame(input);
input_sync(input);
td->num_received = 0;
}
+static void mt_compute_scan_time(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 ms. */
+ delta *= 100;
+
+ if (abs(delta - jdelta) > MAX_SCAN_INTERVAL)
+ /* obviously wrong clock -> the device time has been reset */
+ td->scan_time = 0;
+ else
+ td->scan_time += delta;
+}
+
static int mt_event(struct hid_device *hid, struct hid_field *field,
struct hid_usage *usage, __s32 value)
{
@@ -617,6 +655,9 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
case HID_DG_HEIGHT:
td->curdata.h = value;
break;
+ case HID_DG_SCANTIME:
+ mt_compute_scan_time(td, field, value);
+ break;
case HID_DG_CONTACTCOUNT:
/*
* Includes multi-packet support where subsequent
--
1.7.11.7
--
To unsubscribe from this list: send the line "unsubscribe linux-input" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
