[PATCH] usbhid: Interpret 0 length ff effects as infinite (0xffff) length effects

From: Paul Dino Jones
Date: Sat Oct 01 2022 - 18:13:27 EST


I started using my Accuforce V2 sim wheel on Linux. I was getting no
response from racing simulators through wine, while native linux test
tools worked properly. It appears that many real-world applications will
send 0 as the replay length, which was resulting in the behavior I was
observing (nothing). The PID document does not explicitly state that 0
length effects should be interpreted as infinite, but it does mention
null effects being infinite effects.

This patch will interpret 0 length force feedback effects as 0xffff
(infinite) length effects, leaving other values for replay length

Signed-off-by: Paul Dino Jones <paul@xxxxxxxxxxxxxxxx>
drivers/hid/usbhid/hid-pidff.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/usbhid/hid-pidff.c b/drivers/hid/usbhid/hid-pidff.c
index 3b4ee21cd811..70653451c860 100644
--- a/drivers/hid/usbhid/hid-pidff.c
+++ b/drivers/hid/usbhid/hid-pidff.c
@@ -301,7 +301,7 @@ static void pidff_set_effect_report(struct pidff_device *pidff,
pidff->set_effect_type->value[0] =
- pidff->set_effect[PID_DURATION].value[0] = effect->replay.length;
+ 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] =