linux-kernel - [PATCH] HID: multitouch: do not blindly set EV_KEY or EV

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Date:   Tue, 11 Jul 2017 10:02:18 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     Matthias Fend <Matthias.Fend@...fvision.net>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] HID: multitouch: do not blindly set EV_KEY or EV_ABS bits

Now that input core insists on having dev->absinfo when device claims to
generate EV_ABS in its dev->evbit, we should not be blindly setting that
bit.

The code in question might have been needed before input_set_abs_params()
started setting EV_ABS in device's evbit, but not anymore, and is now
breaking devices such as SMART SPNL-6075 Touchscreen.

Fixes: 6ecfe51b4082 ("Input: refuse to register absolute devices ...")
Reported-by: Matthias Fend <Matthias.Fend@...fvision.net>
Tested-by: Matthias Fend <Matthias.Fend@...fvision.net>
Cc: stable@...r.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---

Jiri, Benjamin, I marked it for stable as it causes regressions in 4.12
reported by users. Please take a look.

 drivers/hid/hid-multitouch.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 24d5b6deb571..be5bea15ce52 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -595,16 +595,6 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 	return 0;
 }
 
-static int mt_touch_input_mapped(struct hid_device *hdev, struct hid_input *hi,
-		struct hid_field *field, struct hid_usage *usage,
-		unsigned long **bit, int *max)
-{
-	if (usage->type == EV_KEY || usage->type == EV_ABS)
-		set_bit(usage->type, hi->input->evbit);
-
-	return -1;
-}
-
 static int mt_compute_slot(struct mt_device *td, struct input_dev *input)
 {
 	__s32 quirks = td->mtclass.quirks;
@@ -905,8 +895,10 @@ static int mt_input_mapped(struct hid_device *hdev, struct hid_input *hi,
 		return 0;
 
 	if (field->application == HID_DG_TOUCHSCREEN ||
-	    field->application == HID_DG_TOUCHPAD)
-		return mt_touch_input_mapped(hdev, hi, field, usage, bit, max);
+	    field->application == HID_DG_TOUCHPAD) {
+		/* We own these mappings, tell hid-input to ignore them */
+		return -1;
+	}
 
 	/* let hid-core decide for the others */
 	return 0;
-- 
2.13.2.725.g09c95d1e9-goog


-- 
Dmitry