linux-kernel - [PATCH 2/5] HID: pidff: Add MISSING_NEG

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260203174531.2866644-3-tomasz.pakula.oficjalny@gmail.com>
Date: Tue,  3 Feb 2026 18:45:28 +0100
From: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>
To: jikos@...nel.org,
	bentiss@...nel.org
Cc: oleg@...arenk.ooo,
	linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	tomasz.pakula.oficjalny@...il.com
Subject: [PATCH 2/5] HID: pidff: Add MISSING_NEG_COEFFICIENT quirk

Windows/Directinput allows devices with missing negative coefficient for
conditional effects. Negative coefficient is ignored in such cases.

Donot fail set_condition usage search if negative coefficient is missing.
Fixes conditional effect playback on Asetek wheelbases.

https://learn.microsoft.com/en-us/previous-versions/windows/desktop/ee416601(v=vs.85)

Co-developed-by: Oleg Makarenko <oleg@...arenk.ooo>
Signed-off-by: Oleg Makarenko <oleg@...arenk.ooo>
Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>
---
 drivers/hid/usbhid/hid-pidff.c | 11 +++++++++--
 drivers/hid/usbhid/hid-pidff.h |  3 +++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/usbhid/hid-pidff.c b/drivers/hid/usbhid/hid-pidff.c
index 68049d5d76b3..aebf6c89643f 100644
--- a/drivers/hid/usbhid/hid-pidff.c
+++ b/drivers/hid/usbhid/hid-pidff.c
@@ -619,8 +619,12 @@ static void pidff_set_condition_report(struct pidff_device *pidff,
 				 effect->u.condition[i].center);
 		pidff_set_signed(&pidff->set_condition[PID_POS_COEFFICIENT],
 				 effect->u.condition[i].right_coeff);
-		pidff_set_signed(&pidff->set_condition[PID_NEG_COEFFICIENT],
-				 effect->u.condition[i].left_coeff);
+
+		/* Omit Negative Coefficient if missing */
+		if (!(pidff->quirks & HID_PIDFF_QUIRK_MISSING_NEG_COEFFICIENT))
+			pidff_set_signed(&pidff->set_condition[PID_NEG_COEFFICIENT],
+					effect->u.condition[i].left_coeff);
+
 		pidff_set(&pidff->set_condition[PID_POS_SATURATION],
 			  effect->u.condition[i].right_saturation);
 		pidff_set(&pidff->set_condition[PID_NEG_SATURATION],
@@ -1090,6 +1094,9 @@ static int pidff_find_fields(struct pidff_usage *usage, const u8 *table,
 		else if (table[i] == pidff_set_condition[PID_PARAM_BLOCK_OFFSET])
 			PIDFF_MISSING_FIELD(PBO, quirks);
 
+		else if (table[i] == pidff_set_condition[PID_NEG_COEFFICIENT])
+			PIDFF_MISSING_FIELD(NEG_COEFFICIENT, quirks);
+
 		else if (strict) {
 			pr_debug("failed to locate %d\n", i);
 			return -1;
diff --git a/drivers/hid/usbhid/hid-pidff.h b/drivers/hid/usbhid/hid-pidff.h
index f321f675e131..5bf54e981543 100644
--- a/drivers/hid/usbhid/hid-pidff.h
+++ b/drivers/hid/usbhid/hid-pidff.h
@@ -21,6 +21,9 @@
 /* Force all periodic effects to be uploaded as SINE */
 #define HID_PIDFF_QUIRK_PERIODIC_SINE_ONLY	BIT(4)
 
+/* Allow devices with missing negative coefficient in the set condition usage */
+#define HID_PIDFF_QUIRK_MISSING_NEG_COEFFICIENT	BIT(5)
+
 #ifdef CONFIG_HID_PID
 int hid_pidff_init(struct hid_device *hid);
 int hid_pidff_init_with_quirks(struct hid_device *hid, u32 initial_quirks);
-- 
2.52.0