[PATCH AUTOSEL 5.4 2/5] HID: pidff: Do not send effect envelope if it's empty
From: Sasha Levin <sashal@kernel.org>
Date: 2025-03-31 14:57:33
Also in:
linux-usb, lkml, stable
Subsystem:
hid core layer, the rest, usb hid pid drivers (usb wheelbases, joysticks, rudders, ...), usb hid/hidbp drivers (usb keyboards, mice, remote controls, ...) · Maintainers:
Jiri Kosina, Benjamin Tissoires, Linus Torvalds, Tomasz Pakuła, Oleg Makarenko
From: Tomasz Pakuła <tomasz.pakula.oficjalny@gmail.com> [ Upstream commit 8876fc1884f5b39550c8387ff3176396c988541d ] Envelope struct is always initialized, but the envelope itself is optional as described in USB PID Device class definition 1.0. 5.1.1.1 Type Specific Block Offsets ... 4) Effects that do not use Condition Blocks use 1 Parameter Block and an *optional* Envelope Block. Sending out "empty" envelope breaks force feedback on some devices with games that use SINE effect + offset to emulate constant force effect, as well as generally breaking Constant/Periodic effects. One of the affected brands is Moza Racing. This change prevents the envelope from being sent if it contains all 0 values while keeping the old behavior of only sending it, if it differs from the old one. Changes in v6: - Simplify the checks to make them clearer - Fix possible null pointer dereference while calling pidff_needs_set_envelope Signed-off-by: Tomasz Pakuła <tomasz.pakula.oficjalny@gmail.com> Reviewed-by: Michał Kopeć <redacted> Reviewed-by: Paul Dino Jones <redacted> Tested-by: Paul Dino Jones <redacted> Tested-by: Cristóferson Bueno <redacted> Tested-by: Pablo Cisneros <redacted> Signed-off-by: Jiri Kosina <redacted> Signed-off-by: Sasha Levin <sashal@kernel.org> --- drivers/hid/usbhid/hid-pidff.c | 42 +++++++++++++++++++--------------- 1 file changed, 24 insertions(+), 18 deletions(-)
diff --git a/drivers/hid/usbhid/hid-pidff.c b/drivers/hid/usbhid/hid-pidff.c
index badcb5f28607e..ba0d7cb15377e 100644
--- a/drivers/hid/usbhid/hid-pidff.c
+++ b/drivers/hid/usbhid/hid-pidff.c@@ -262,10 +262,22 @@ static void pidff_set_envelope_report(struct pidff_device *pidff, static int pidff_needs_set_envelope(struct ff_envelope *envelope, struct ff_envelope *old) { - return envelope->attack_level != old->attack_level || - envelope->fade_level != old->fade_level || + bool needs_new_envelope; + needs_new_envelope = envelope->attack_level != 0 || + envelope->fade_level != 0 || + envelope->attack_length != 0 || + envelope->fade_length != 0; + + if (!needs_new_envelope) + return false; + + if (!old) + return needs_new_envelope; + + return envelope->attack_level != old->attack_level || + envelope->fade_level != old->fade_level || envelope->attack_length != old->attack_length || - envelope->fade_length != old->fade_length; + envelope->fade_length != old->fade_length; } /*
@@ -580,11 +592,9 @@ static int pidff_upload_effect(struct input_dev *dev, struct ff_effect *effect, pidff_set_effect_report(pidff, effect); if (!old || pidff_needs_set_constant(effect, old)) pidff_set_constant_force_report(pidff, effect); - if (!old || - pidff_needs_set_envelope(&effect->u.constant.envelope, - &old->u.constant.envelope)) - pidff_set_envelope_report(pidff, - &effect->u.constant.envelope); + if (pidff_needs_set_envelope(&effect->u.constant.envelope, + old ? &old->u.constant.envelope : NULL)) + pidff_set_envelope_report(pidff, &effect->u.constant.envelope); break; case FF_PERIODIC:
@@ -619,11 +629,9 @@ static int pidff_upload_effect(struct input_dev *dev, struct ff_effect *effect, pidff_set_effect_report(pidff, effect); if (!old || pidff_needs_set_periodic(effect, old)) pidff_set_periodic_report(pidff, effect); - if (!old || - pidff_needs_set_envelope(&effect->u.periodic.envelope, - &old->u.periodic.envelope)) - pidff_set_envelope_report(pidff, - &effect->u.periodic.envelope); + if (pidff_needs_set_envelope(&effect->u.periodic.envelope, + old ? &old->u.periodic.envelope : NULL)) + pidff_set_envelope_report(pidff, &effect->u.periodic.envelope); break; case FF_RAMP:
@@ -637,11 +645,9 @@ static int pidff_upload_effect(struct input_dev *dev, struct ff_effect *effect, pidff_set_effect_report(pidff, effect); if (!old || pidff_needs_set_ramp(effect, old)) pidff_set_ramp_force_report(pidff, effect); - if (!old || - pidff_needs_set_envelope(&effect->u.ramp.envelope, - &old->u.ramp.envelope)) - pidff_set_envelope_report(pidff, - &effect->u.ramp.envelope); + if (pidff_needs_set_envelope(&effect->u.ramp.envelope, + old ? &old->u.ramp.envelope : NULL)) + pidff_set_envelope_report(pidff, &effect->u.ramp.envelope); break; case FF_SPRING:
--
2.39.5