[PATCH 16/21] HID: zeroplus: move FF initialization to .input_configured()

[Dmitry Torokhov]

The driver currently initializes force-feedback in its probe() function
after calling hid_hw_start(). This is racy as the input device is
already registered and visible to userspace at that point.

Move the FF initialization to the .input_configured() callback to ensure
the device is fully prepared before registration.

Assisted-by: Gemini:gemini-3.1-pro
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
---
 drivers/hid/hid-zpff.c | 43 ++++++++-----------------------------------
 1 file changed, 8 insertions(+), 35 deletions(-)

diff --git a/drivers/hid/hid-zpff.c b/drivers/hid/hid-zpff.c
index d8e023c8aa84..b565c59d3dfe 100644
--- a/drivers/hid/hid-zpff.c
+++ b/drivers/hid/hid-zpff.c
@@ -50,20 +50,15 @@ static int zpff_play(struct input_dev *dev, void *data,
 	return 0;
 }
 
-static int zpff_init(struct hid_device *hid)
+static int zp_input_configured(struct hid_device *hid, struct hid_input *hidinput)
 {
 	struct zpff_device *zpff;
 	struct hid_report *report;
-	struct hid_input *hidinput;
-	struct input_dev *dev;
+	struct input_dev *dev = hidinput->input;
 	int i, error;
 
-	if (list_empty(&hid->inputs)) {
-		hid_err(hid, "no inputs found\n");
-		return -ENODEV;
-	}
-	hidinput = list_entry(hid->inputs.next, struct hid_input, list);
-	dev = hidinput->input;
+	if (!list_is_first(&hidinput->list, &hid->inputs))
+		return 0;
 
 	for (i = 0; i < 4; i++) {
 		report = hid_validate_values(hid, HID_OUTPUT_REPORT, 0, i, 1);
@@ -75,6 +70,7 @@ static int zpff_init(struct hid_device *hid)
 	if (!zpff)
 		return -ENOMEM;
 
+	zpff->report = report;
 	set_bit(FF_RUMBLE, dev->ffbit);
 
 	error = input_ff_create_memless(dev, zpff, zpff_play);
@@ -83,7 +79,6 @@ static int zpff_init(struct hid_device *hid)
 		return error;
 	}
 
-	zpff->report = report;
 	zpff->report->field[0]->value[0] = 0x00;
 	zpff->report->field[1]->value[0] = 0x02;
 	zpff->report->field[2]->value[0] = 0x00;
@@ -95,35 +90,13 @@ static int zpff_init(struct hid_device *hid)
 	return 0;
 }
 #else
-static inline int zpff_init(struct hid_device *hid)
+static inline int zp_input_configured(struct hid_device *hid,
+				      struct hid_input *hidinput)
 {
 	return 0;
 }
 #endif
 
-static int zp_probe(struct hid_device *hdev, const struct hid_device_id *id)
-{
-	int ret;
-
-	ret = hid_parse(hdev);
-	if (ret) {
-		hid_err(hdev, "parse failed\n");
-		goto err;
-	}
-
-	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
-	if (ret) {
-		hid_err(hdev, "hw start failed\n");
-		goto err;
-	}
-
-	zpff_init(hdev);
-
-	return 0;
-err:
-	return ret;
-}
-
 static const struct hid_device_id zp_devices[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_ZEROPLUS, 0x0005) },
 	{ HID_USB_DEVICE(USB_VENDOR_ID_ZEROPLUS, 0x0030) },
@@ -134,7 +107,7 @@ MODULE_DEVICE_TABLE(hid, zp_devices);
 static struct hid_driver zp_driver = {
 	.name = "zeroplus",
 	.id_table = zp_devices,
-	.probe = zp_probe,
+	.input_configured = zp_input_configured,
 };
 module_hid_driver(zp_driver);
 

-- 
2.55.0.629.g250fe7f194-goog