[PATCH 14/21] HID: pantherlord: 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-pl.c | 150 ++++++++++++++++++++++-----------------------------
 1 file changed, 65 insertions(+), 85 deletions(-)

diff --git a/drivers/hid/hid-pl.c b/drivers/hid/hid-pl.c
index 8bba29ef6c7a..cae56a6c941b 100644
--- a/drivers/hid/hid-pl.c
+++ b/drivers/hid/hid-pl.c
@@ -62,15 +62,13 @@ static int hid_plff_play(struct input_dev *dev, void *data,
 	return 0;
 }
 
-static int plff_init(struct hid_device *hid)
+static int pl_input_configured(struct hid_device *hid, struct hid_input *hidinput)
 {
 	struct plff_device *plff;
 	struct hid_report *report;
-	struct hid_input *hidinput;
 	struct list_head *report_list =
 			&hid->report_enum[HID_OUTPUT_REPORT].report_list;
-	struct list_head *report_ptr = report_list;
-	struct input_dev *dev;
+	struct input_dev *dev = hidinput->input;
 	int error;
 	s32 maxval;
 	s32 *strong;
@@ -83,89 +81,80 @@ static int plff_init(struct hid_device *hid)
 	   The input reports also contain a field which contains
 	   8 ff00.0001 usages and 8 boolean values. Their meaning is
 	   currently unknown.
-	   
+
 	   A version of the 0e8f:0003 exists that has all the values in
 	   separate fields and misses the extra input field, thus resembling
 	   Zeroplus (hid-zpff) devices.
 	*/
 
-	if (list_empty(report_list)) {
+	if (!list_is_first(&hidinput->list, &hid->inputs))
+		return 0;
+
+	report = list_first_entry_or_null(report_list, struct hid_report, list);
+	if (!report) {
 		hid_err(hid, "no output reports found\n");
 		return -ENODEV;
 	}
+	if (report->maxfield < 1) {
+		hid_err(hid, "no fields in the report\n");
+		return -ENODEV;
+	}
 
-	list_for_each_entry(hidinput, &hid->inputs, list) {
-
-		report_ptr = report_ptr->next;
-
-		if (report_ptr == report_list) {
-			hid_err(hid, "required output report is missing\n");
-			return -ENODEV;
-		}
-
-		report = list_entry(report_ptr, struct hid_report, list);
-		if (report->maxfield < 1) {
-			hid_err(hid, "no fields in the report\n");
-			return -ENODEV;
-		}
-
-		maxval = 0x7f;
-		if (report->field[0]->report_count >= 4) {
-			report->field[0]->value[0] = 0x00;
-			report->field[0]->value[1] = 0x00;
-			strong = &report->field[0]->value[2];
-			weak = &report->field[0]->value[3];
-			hid_dbg(hid, "detected single-field device");
-		} else if (report->field[0]->maxusage == 1 &&
-			   report->field[0]->usage[0].hid ==
-				(HID_UP_LED | 0x43) &&
-			   report->maxfield >= 4 &&
-			   report->field[0]->report_count >= 1 &&
-			   report->field[1]->report_count >= 1 &&
-			   report->field[2]->report_count >= 1 &&
-			   report->field[3]->report_count >= 1) {
-			report->field[0]->value[0] = 0x00;
-			report->field[1]->value[0] = 0x00;
-			strong = &report->field[2]->value[0];
-			weak = &report->field[3]->value[0];
-			if (hid->vendor == USB_VENDOR_ID_JESS2)
-				maxval = 0xff;
-			hid_dbg(hid, "detected 4-field device");
-		} else {
-			hid_err(hid, "not enough fields or values\n");
-			return -ENODEV;
-		}
-
-		plff = kzalloc_obj(struct plff_device);
-		if (!plff)
-			return -ENOMEM;
-
-		dev = hidinput->input;
-
-		set_bit(FF_RUMBLE, dev->ffbit);
-
-		error = input_ff_create_memless(dev, plff, hid_plff_play);
-		if (error) {
-			kfree(plff);
-			return error;
-		}
-
-		plff->report = report;
-		plff->strong = strong;
-		plff->weak = weak;
-		plff->maxval = maxval;
-
-		*strong = 0x00;
-		*weak = 0x00;
-		hid_hw_request(hid, plff->report, HID_REQ_SET_REPORT);
+	maxval = 0x7f;
+	if (report->field[0]->report_count >= 4) {
+		report->field[0]->value[0] = 0x00;
+		report->field[0]->value[1] = 0x00;
+		strong = &report->field[0]->value[2];
+		weak = &report->field[0]->value[3];
+		hid_dbg(hid, "detected single-field device");
+	} else if (report->field[0]->maxusage == 1 &&
+		   report->field[0]->usage[0].hid ==
+			(HID_UP_LED | 0x43) &&
+		   report->maxfield >= 4 &&
+		   report->field[0]->report_count >= 1 &&
+		   report->field[1]->report_count >= 1 &&
+		   report->field[2]->report_count >= 1 &&
+		   report->field[3]->report_count >= 1) {
+		report->field[0]->value[0] = 0x00;
+		report->field[1]->value[0] = 0x00;
+		strong = &report->field[2]->value[0];
+		weak = &report->field[3]->value[0];
+		if (hid->vendor == USB_VENDOR_ID_JESS2)
+			maxval = 0xff;
+		hid_dbg(hid, "detected 4-field device");
+	} else {
+		hid_err(hid, "not enough fields or values\n");
+		return -ENODEV;
 	}
 
-	hid_info(hid, "Force feedback for PantherLord/GreenAsia devices by Anssi Hannula <anssi.hannula@xxxxxxxxx>\n");
+	plff = kzalloc_obj(struct plff_device);
+	if (!plff)
+		return -ENOMEM;
+
+	dev = hidinput->input;
+
+	set_bit(FF_RUMBLE, dev->ffbit);
+
+	error = input_ff_create_memless(dev, plff, hid_plff_play);
+	if (error) {
+		kfree(plff);
+		return error;
+	}
+
+	plff->report = report;
+	plff->strong = strong;
+	plff->weak = weak;
+	plff->maxval = maxval;
+
+	*strong = 0x00;
+	*weak = 0x00;
+	hid_hw_request(hid, plff->report, HID_REQ_SET_REPORT);
 
 	return 0;
 }
 #else
-static inline int plff_init(struct hid_device *hid)
+static inline int pl_input_configured(struct hid_device *hid,
+				      struct hid_input *hidinput)
 {
 	return 0;
 }
@@ -181,27 +170,17 @@ static int pl_probe(struct hid_device *hdev, const struct hid_device_id *id)
 	ret = hid_parse(hdev);
 	if (ret) {
 		hid_err(hdev, "parse failed\n");
-		goto err;
+		return ret;
 	}
 
-	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
 	if (ret) {
 		hid_err(hdev, "hw start failed\n");
-		goto err;
+		return ret;
 	}
 
-	ret = plff_init(hdev);
-	if (ret)
-		goto stop;
-
 	return 0;
-
-stop:
-	hid_hw_stop(hdev);
-err:
-	return ret;
 }
-
 static const struct hid_device_id pl_devices[] = {
 	{ HID_USB_DEVICE(USB_VENDOR_ID_GAMERON, USB_DEVICE_ID_GAMERON_DUAL_PSX_ADAPTOR),
 		.driver_data = 1 }, /* Twin USB Joystick */
@@ -217,6 +196,7 @@ static struct hid_driver pl_driver = {
 	.name = "pantherlord",
 	.id_table = pl_devices,
 	.probe = pl_probe,
+	.input_configured = pl_input_configured,
 };
 module_hid_driver(pl_driver);
 

-- 
2.55.0.629.g250fe7f194-goog