With this, these devices now behave as tablets as expected by userspace
The search in hidinput_is_win8_touching() terminates at f=0, u=0
on Goodix screens (27C6:0111, 27C6:0113), but I expect it
to have negligible impact on devices that don't have TipSwitch
as the first report as well
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@xxxxxxxxxxxxxxxxxx>
---
Notes:
changes in v2:
* hidinput_fixup_win8_inrange() became hidinput_is_win8_touching()
* BarrelSwitch now anded with TipSwitch
drivers/hid/hid-input.c | 48 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index a5ba92978473..aee1f1283c1d 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -1273,6 +1273,42 @@ static void hidinput_handle_scroll(struct hid_usage *usage,
input_event(input, EV_REL, usage->code, hi_res);
}
+/*
+ * Win8 tablet stylus devices send, in order:
+ * HID_DG_TIPSWITCH (BTN_TOUCH)
+ * HID_DG_INVERT (BTN_TOOL_RUBBER)
+ * HID_DG_ERASER (BTN_TOUCH)
+ * HID_DG_INRANGE (BTN_TOOL_PEN)
+ *
+ * For each of these states:
+ * hover : INRANGE
+ * touching : TIPSWITCH
+ * hover+2 : INVERT INRANGE
+ * touching+2: ERASER INRANGE
+ *
+ * Which means we'd send BTN_TOUCH=0 + BTN_TOOL_PEN=1 on proximity,
+ * then BTN_TOUCH=1 and BTN_TOOL_PEN=0 in consecutive groups when touched,
+ * indicating the stylus leaving the screen as soon as the two meet.
+ *
+ * Additionally, HID_DG_BARRELSWITCH corresponds directly to the button,
+ * regardless of the tip switch, making it borderline impossible to use precisely.
+ */
+static bool hidinput_is_win8_touching(struct hid_device *hid, struct hid_field *field)
+{
+ unsigned f, u;
+ struct hid_field *rfield;
+
+ for (f = 0; f < field->report->maxfield; ++f) {
+ rfield = field->report->field[f];
+ for (u = 0; u < rfield->maxusage; ++u) {
+ if (rfield->usage[u].hid == HID_DG_TIPSWITCH)
+ return rfield->value[u];
+ }
+ }
+
+ return false;
+}
+
void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct hid_usage *usage, __s32 value)
{
struct input_dev *input;
@@ -1306,7 +1342,13 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct
return;
}
+ if (usage->hid == HID_DG_ERASER && value)
+ *quirks |= HID_QUIRK_INVERT;
+
if (usage->hid == HID_DG_INRANGE) {
+ if (hid->group == HID_GROUP_MULTITOUCH_WIN_8)
+ value = value || hidinput_is_win8_touching(hid, field);
+
if (value) {
input_event(input, usage->type, (*quirks & HID_QUIRK_INVERT) ? BTN_TOOL_RUBBER : usage->code, 1);
return;
@@ -1322,6 +1364,12 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct
input_event(input, EV_KEY, BTN_TOUCH, value > a + ((b - a) >> 3));
}
+ if (usage->hid == HID_DG_BARRELSWITCH && hid->group == HID_GROUP_MULTITOUCH_WIN_8) {
+ value = value && hidinput_is_win8_touching(hid, field);
+ input_event(input, usage->type, usage->code, value);
+ return;
+ }
+
if (usage->hid == (HID_UP_PID | 0x83UL)) { /* Simultaneous Effects Max */
dbg_hid("Maximum Effects - %d\n",value);
return;
--
2.20.1
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