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[v2,01/10] HID: pidff: Convert infinite length from Linux API to PID standard

Message ID 20250105193628.296350-2-tomasz.pakula.oficjalny@gmail.com (mailing list archive)
State Superseded
Delegated to: Jiri Kosina
Headers show
Series HID: Upgrade the generic pidff driver and add hid-universal-pidff | expand

Commit Message

Tomasz Pakuła Jan. 5, 2025, 7:36 p.m. UTC 
Linux defines 0 length as infinite in its force feedback API
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@makarenk.ooo>
Signed-off-by: Makarenko Oleg <oleg@makarenk.ooo>
Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@gmail.com>
---
 drivers/hid/usbhid/hid-pidff.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/hid/usbhid/hid-pidff.c b/drivers/hid/usbhid/hid-pidff.c
index 3b4ee21cd811..3899d72a0b02 100644
--- a/drivers/hid/usbhid/hid-pidff.c
+++ b/drivers/hid/usbhid/hid-pidff.c
@@ -301,7 +301,12 @@  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 ? 0xffff : 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;