From: Siarhei Vishniakou Date: Tue, 11 Nov 2025 23:45:19 +0000 (-0800) Subject: HID: playstation: Center initial joystick axes to prevent spurious events X-Git-Tag: v6.19-rc5~30^2~19 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e9143268d259d98e111a649affa061acb8e13c5b;p=thirdparty%2Fkernel%2Flinux.git HID: playstation: Center initial joystick axes to prevent spurious events When a new PlayStation gamepad (DualShock 4 or DualSense) is initialized, the input subsystem sets the default value for its absolute axes (e.g., ABS_X, ABS_Y) to 0. However, the hardware's actual neutral/resting state for these joysticks is 128 (0x80). This creates a mismatch. When the first HID report arrives from the device, the driver sees the resting value of 128. The kernel compares this to its initial state of 0 and incorrectly interprets this as a delta (0 -> 128). Consequently, it generates EV_ABS events for this initial, non-existent movement. This behavior can fail userspace 'sanity check' tests (e.g., in Android CTS) that correctly assert no motion events should be generated from a device that is already at rest. This patch fixes the issue by explicitly setting the initial value of the main joystick axes (e.g., ABS_X, ABS_Y, ABS_RX, ABS_RY) to 128 (0x80) in the common ps_gamepad_create() function. This aligns the kernel's initial state with the hardware's expected neutral state, ensuring that the first report (at 128) produces no delta and thus, no spurious event. Signed-off-by: Siarhei Vishniakou Reviewed-by: Benjamin Tissoires Signed-off-by: Benjamin Tissoires --- diff --git a/drivers/hid/hid-playstation.c b/drivers/hid/hid-playstation.c index 128aa6abd10b..e4dfcf26b04e 100644 --- a/drivers/hid/hid-playstation.c +++ b/drivers/hid/hid-playstation.c @@ -753,11 +753,16 @@ ps_gamepad_create(struct hid_device *hdev, if (IS_ERR(gamepad)) return ERR_CAST(gamepad); + /* Set initial resting state for joysticks to 128 (center) */ input_set_abs_params(gamepad, ABS_X, 0, 255, 0, 0); + gamepad->absinfo[ABS_X].value = 128; input_set_abs_params(gamepad, ABS_Y, 0, 255, 0, 0); + gamepad->absinfo[ABS_Y].value = 128; input_set_abs_params(gamepad, ABS_Z, 0, 255, 0, 0); input_set_abs_params(gamepad, ABS_RX, 0, 255, 0, 0); + gamepad->absinfo[ABS_RX].value = 128; input_set_abs_params(gamepad, ABS_RY, 0, 255, 0, 0); + gamepad->absinfo[ABS_RY].value = 128; input_set_abs_params(gamepad, ABS_RZ, 0, 255, 0, 0); input_set_abs_params(gamepad, ABS_HAT0X, -1, 1, 0, 0);