linux-kernel - [PATCH] ANDROID: Fix the HID usage of DPAD input event generation.

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Message-Id: <20201028235150.662864-1-lzye@google.com>
Date:   Wed, 28 Oct 2020 16:51:50 -0700
From:   FirstName LastName <lzye@...gle.com>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>,
        Mark Brown <broonie@...nel.org>
Cc:     linzhao.ye@...il.com, linux-kernel@...r.kernel.org,
        trivial@...nel.org, stable@...r.kernel.org,
        Chris Ye <lzye@...gle.com>
Subject: [PATCH] ANDROID: Fix the HID usage of DPAD input event generation.

From: Chris Ye <lzye@...gle.com>

Generic Desktop DPAD usage is mapped by hid-input, that only the first
DPAD usage maps to usage type EV_ABS and code of an axis. If HID
descriptor has DPAD UP/DOWN/LEFT/RIGHT HID usages and each of usage size
is 1 bit, then only the first one will generate input event, the rest of
the HID usages will be assigned to hat direction only.
The hid input event should check the HID report value and generate
HID event for its hat direction.

Test: Connect HID device with Generic Desktop DPAD usage and press the
DPAD to generate input events.

Signed-off-by: Chris Ye <lzye@...gle.com>
---
 drivers/hid/hid-input.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index 9770db624bfa..6c1007de3409 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -1269,7 +1269,7 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct
 	struct input_dev *input;
 	unsigned *quirks = &hid->quirks;
 
-	if (!usage->type)
+	if (!usage->type && !field->dpad)
 		return;
 
 	if (usage->type == EV_PWR) {
@@ -1286,9 +1286,17 @@ void hidinput_hid_event(struct hid_device *hid, struct hid_field *field, struct
 		int hat_dir = usage->hat_dir;
 		if (!hat_dir)
 			hat_dir = (value - usage->hat_min) * 8 / (usage->hat_max - usage->hat_min + 1) + 1;
-		if (hat_dir < 0 || hat_dir > 8) hat_dir = 0;
-		input_event(input, usage->type, usage->code    , hid_hat_to_axis[hat_dir].x);
-		input_event(input, usage->type, usage->code + 1, hid_hat_to_axis[hat_dir].y);
+		if (hat_dir < 0 || hat_dir > 8 || value == 0)
+			hat_dir = 0;
+		if (field->dpad) {
+			input_event(input, EV_ABS, field->dpad, hid_hat_to_axis[hat_dir].x);
+			input_event(input, EV_ABS, field->dpad + 1, hid_hat_to_axis[hat_dir].y);
+		} else {
+			input_event(input, usage->type, usage->code,
+				hid_hat_to_axis[hat_dir].x);
+			input_event(input, usage->type, usage->code + 1,
+				hid_hat_to_axis[hat_dir].y);
+		}
 		return;
 	}
 
-- 
2.29.1.341.ge80a0c044ae-goog