[v7,01/17] HID: pidff: Convert infinite length from Linux API to PID standard

Commit Message

Tomasz Pakuła Jan. 25, 2025, 10:25 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 <[e-mail]>
Signed-off-by: Makarenko Oleg <[e-mail]>
Signed-off-by: Tomasz Pakuła <[e-mail]>
---
 drivers/hid/usbhid/hid-pidff.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Patch

diff --git a/drivers/hid/usbhid/hid-pidff.c b/drivers/hid/usbhid/hid-pidff.c
index 3b4ee21cd811..5fe4422bb5ba 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;