On Nov 07 2017 or thereabouts, Hans de Goede wrote:
> The Windows Precision Touchpad spec "Figure 4 Button Only Down and Up"
> and "Table 9 Report Sequence for Button Only Down and Up" indicate
> that the first packet of a (possibly hybrid mode multi-packet) frame
> may contain a contact-count of 0 if only a button is pressed and no
> fingers are detected.
>
> This means that a value of 0 for contact-count is a valid value and
> should be used as expected contact count when it is the first packet
> (num_received == 0), as extra check to make sure that this is the first
> packet of a buttons only frame, we also check that the timestamp is
> different.
>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
This one is
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
Cheers,
Benjamin
> Changes in v2:
> -New patch in v2 of this patch-set
>
> Changes in v3:
> -Also check timestamps to make sure we're dealing with the first-packet
> of a frame
> ---
> drivers/hid/hid-multitouch.c | 34 ++++++++++++++++++++++++++++++++--
> include/linux/hid.h | 1 +
> 2 files changed, 33 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index bb939f6990f1..5d3904d0e89d 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -117,6 +117,9 @@ struct mt_device {
> unsigned long mt_io_flags; /* mt flags (MT_IO_FLAGS_*) */
> int cc_index; /* contact count field index in the report */
> int cc_value_index; /* contact count value index in the field */
> + int scantime_index; /* scantime field index in the report */
> + int scantime_val_index; /* scantime value index in the field */
> + int prev_scantime; /* scantime reported in the previous packet */
> unsigned last_slot_field; /* the last field of a slot */
> unsigned mt_report_id; /* the report ID of the multitouch device */
> unsigned long initial_quirks; /* initial quirks state */
> @@ -595,6 +598,14 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
> /* we don't set td->last_slot_field as contactcount and
> * contact max are global to the report */
> return -1;
> + case HID_DG_SCANTIME:
> + /* Ignore if indexes are out of bounds. */
> + if (field->index >= field->report->maxfield ||
> + usage->usage_index >= field->report_count)
> + return 1;
> + td->scantime_index = field->index;
> + td->scantime_val_index = usage->usage_index;
> + return 1;
> case HID_DG_TOUCH:
> /* Legacy devices use TIPSWITCH and not TOUCH.
> * Let's just ignore this field. */
> @@ -812,9 +823,10 @@ static void mt_process_mt_event(struct hid_device *hid, struct hid_field *field,
> static void mt_touch_report(struct hid_device *hid, struct hid_report *report)
> {
> struct mt_device *td = hid_get_drvdata(hid);
> + __s32 cls = td->mtclass.name;
> struct hid_field *field;
> unsigned count;
> - int r, n;
> + int r, n, scantime = 0;
>
> /* sticky fingers release in progress, abort */
> if (test_and_set_bit(MT_IO_FLAGS_RUNNING, &td->mt_io_flags))
> @@ -824,12 +836,29 @@ static void mt_touch_report(struct hid_device *hid, struct hid_report *report)
> * Includes multi-packet support where subsequent
> * packets are sent with zero contactcount.
> */
> + if (td->scantime_index >= 0) {
> + field = report->field[td->scantime_index];
> + scantime = field->value[td->scantime_val_index];
> + }
> if (td->cc_index >= 0) {
> struct hid_field *field = report->field[td->cc_index];
> int value = field->value[td->cc_value_index];
> - if (value)
> +
> + /*
> + * For Win8 PTPs the first packet (td->num_received == 0) may
> + * have a contactcount of 0 if there only is a button event.
> + * We double check that this is not a continuation packet
> + * of a possible multi-packet frame be checking that the
> + * timestamp has changed.
> + */
> + if ((cls == MT_CLS_WIN_8 || cls == MT_CLS_WIN_8_DUAL) &&
> + td->num_received == 0 && td->prev_scantime != scantime)
> + td->num_expected = value;
> + /* A non 0 contact count always indicates a first packet */
> + else if (value)
> td->num_expected = value;
> }
> + td->prev_scantime = scantime;
>
> for (r = 0; r < report->maxfield; r++) {
> field = report->field[r];
> @@ -1285,6 +1314,7 @@ static int mt_probe(struct hid_device *hdev, const struct hid_device_id *id)
> td->maxcontact_report_id = -1;
> td->inputmode_value = MT_INPUTMODE_TOUCHSCREEN;
> td->cc_index = -1;
> + td->scantime_index = -1;
> td->mt_report_id = -1;
> hid_set_drvdata(hdev, td);
>
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index ab05a86269dc..47dd962d9a7a 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -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
> --
> 2.14.3
>
--
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
