linux-kernel - [PATCH AUTOSEL 6.1 1/9] HID: pidff: Convert infinite length from Linux API to PID standard

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Message-Id: <20250331145642.1706037-1-sashal@kernel.org>
Date: Mon, 31 Mar 2025 10:56:34 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>,
	Makarenko Oleg <oleg@...arenk.ooo>,
	Michał Kopeć <michal@...omi.space>,
	Paul Dino Jones <paul@...cefreak18.xyz>,
	Cristóferson Bueno <cbueno81@...il.com>,
	Pablo Cisneros <patchkez@...tonmail.com>,
	Jiri Kosina <jkosina@...e.com>,
	Sasha Levin <sashal@...nel.org>,
	jikos@...nel.org,
	bentiss@...nel.org,
	linux-usb@...r.kernel.org,
	linux-input@...r.kernel.org
Subject: [PATCH AUTOSEL 6.1 1/9] HID: pidff: Convert infinite length from Linux API to PID standard

From: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>

[ Upstream commit 37e0591fe44dce39d1ebc7a82d5b6e4dba1582eb ]

Software uses 0 as de-facto infinite lenght on Linux FF apis (SDL),
Linux doesn't actually define anythi as of now, while USB PID defines
NULL (0xffff). Most PID devices do not expect a 0-length effect and
can't interpret it as infinite. This change fixes Force Feedback for
most PID compliant devices.

As most games depend on updating the values of already playing infinite
effects, this is crucial to ensure they will actually work.

Previously, users had to rely on third-party software to do this conversion
and make their PID devices usable.

Co-developed-by: Makarenko Oleg <oleg@...arenk.ooo>
Signed-off-by: Makarenko Oleg <oleg@...arenk.ooo>
Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@...il.com>
Reviewed-by: Michał Kopeć <michal@...omi.space>
Reviewed-by: Paul Dino Jones <paul@...cefreak18.xyz>
Tested-by: Paul Dino Jones <paul@...cefreak18.xyz>
Tested-by: Cristóferson Bueno <cbueno81@...il.com>
Tested-by: Pablo Cisneros <patchkez@...tonmail.com>
Signed-off-by: Jiri Kosina <jkosina@...e.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/hid/usbhid/hid-pidff.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/usbhid/hid-pidff.c b/drivers/hid/usbhid/hid-pidff.c
index 3b4ee21cd8111..5fe4422bb5bad 100644
--- a/drivers/hid/usbhid/hid-pidff.c
+++ b/drivers/hid/usbhid/hid-pidff.c
@@ -21,6 +21,7 @@
 #include "usbhid.h"
 
 #define	PID_EFFECTS_MAX		64
+#define	PID_INFINITE		0xffff
 
 /* Report usage table used to put reports into an array */
 
@@ -301,7 +302,12 @@ static void pidff_set_effect_report(struct pidff_device *pidff,
 		pidff->block_load[PID_EFFECT_BLOCK_INDEX].value[0];
 	pidff->set_effect_type->value[0] =
 		pidff->create_new_effect_type->value[0];
-	pidff->set_effect[PID_DURATION].value[0] = effect->replay.length;
+
+	/* Convert infinite length from Linux API (0)
+	   to PID standard (NULL) if needed */
+	pidff->set_effect[PID_DURATION].value[0] =
+		effect->replay.length == 0 ? PID_INFINITE : effect->replay.length;
+
 	pidff->set_effect[PID_TRIGGER_BUTTON].value[0] = effect->trigger.button;
 	pidff->set_effect[PID_TRIGGER_REPEAT_INT].value[0] =
 		effect->trigger.interval;
-- 
2.39.5