From: Angela Czubak <aczubak@google.com>
Date: Mon, 18 Aug 2025 23:08:48 +0000 (+0000)
Subject: HID: input: calculate resolution for pressure
X-Git-Tag: v6.18-rc1~81^2~7^2~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7657bf0b7cfb63ded95a6fe4e1cf106cf386b6cc;p=thirdparty%2Flinux.git

HID: input: calculate resolution for pressure

Assume that if the pressure is given in newtons it should be normalized
to grams. If the pressure has no unit do not calculate resolution.

Signed-off-by: Angela Czubak <aczubak@google.com>
Co-developed-by: Jonathan Denose <jdenose@google.com>
Signed-off-by: Jonathan Denose <jdenose@google.com>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
---

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index f6a920fe3102e..5d7532d79d21c 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -303,6 +303,19 @@ __s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code)
 		}
 		break;
 
+	case ABS_PRESSURE:
+	case ABS_MT_PRESSURE:
+		if (field->unit == HID_UNIT_NEWTON) {
+			/* Convert to grams, 1 newton is 101.97 grams */
+			prev = physical_extents;
+			physical_extents *= 10197;
+			if (physical_extents < prev)
+				return 0;
+			unit_exponent -= 2;
+		} else if (field->unit != HID_UNIT_GRAM) {
+			return 0;
+		}
+		break;
 	default:
 		return 0;
 	}