From bebeca20ab377dc0d28ca7f3400c6008ba7f15af Mon Sep 17 00:00:00 2001 From: Sriman Achanta Date: Mon, 3 Aug 2026 15:15:52 -0400 Subject: [PATCH] HID: steelseries: Add async status interface support Some headsets expose a second HID interface that sends battery and connection updates on its own. Watching that interface lets the driver stop polling the sync interface. Add a steelseries_device_info::async_interface field and the code to handle it: - The driver binds both the sync and async interfaces. The async interface shares the steelseries_device created by the sync interface. It finds the sibling with usb_ifnum_to_if(), and before trusting its intfdata it rejects non-HID siblings by descriptor class and holds the sibling's device lock across the lookup, so a crafted device cannot cause a type-confused read and a concurrent unbind cannot free the hid_device from under it. It then takes a reference and returns -EPROBE_DEFER until the sync interface has probed. If the sync interface never binds, the async interface defers forever, which is fine here. - raw_event() now holds sd->lock and re-checks sd->removed so events on either interface are serialised against removal. - status_work runs once for async devices instead of rearming. A single status request is sent when the headset connects to get the initial battery level. No device sets async_interface yet. This is the infrastructure for the next commit. Signed-off-by: Sriman Achanta Signed-off-by: Jiri Kosina --- drivers/hid/hid-steelseries-arctis.c | 154 ++++++++++++++++++++++----- 1 file changed, 129 insertions(+), 25 deletions(-) diff --git a/drivers/hid/hid-steelseries-arctis.c b/drivers/hid/hid-steelseries-arctis.c index e534aa44e70a..9960c0ec512b 100644 --- a/drivers/hid/hid-steelseries-arctis.c +++ b/drivers/hid/hid-steelseries-arctis.c @@ -26,6 +26,7 @@ struct steelseries_device_info { unsigned long capabilities; u8 sync_interface; + u8 async_interface; int (*request_status)(struct hid_device *hdev); void (*parse_status)(struct steelseries_device *sd, u8 *data, int size); @@ -271,7 +272,8 @@ static void steelseries_status_timer_work_handler(struct work_struct *work) sd->info->request_status(sd->hdev); spin_lock_irqsave(&sd->lock, flags); - if (!sd->removed) + /* Async devices push status events themselves; only poll once. */ + if (!sd->removed && !sd->info->async_interface) schedule_delayed_work(&sd->status_work, msecs_to_jiffies(STEELSERIES_HEADSET_STATUS_TIMEOUT_MS)); spin_unlock_irqrestore(&sd->lock, flags); @@ -318,6 +320,53 @@ static int steelseries_battery_register(struct steelseries_device *sd) return 0; } +static struct hid_driver steelseries_arctis_driver; + +static struct steelseries_device * +steelseries_get_sibling_sd(struct hid_device *hdev, int interface_num) +{ + struct usb_interface *intf = to_usb_interface(hdev->dev.parent); + struct usb_device *usb_dev = interface_to_usbdev(intf); + struct usb_interface *sibling_intf; + struct hid_device *sibling_hdev; + struct steelseries_device *sd = NULL; + + sibling_intf = usb_ifnum_to_if(usb_dev, interface_num); + if (!sibling_intf) + return NULL; + + /* + * usb_get_intfdata() only yields a hid_device when usbhid is bound; + * gate on the descriptor class so a non-HID sibling (e.g. a crafted + * device exposing storage or audio here) is never treated as one. + */ + if (sibling_intf->cur_altsetting->desc.bInterfaceClass != USB_INTERFACE_CLASS_HID) + return NULL; + + /* + * Take the sibling's device lock across the intfdata read and the + * kref_get so a concurrent unbind cannot free the hid_device underneath + * us; usbhid leaves intfdata dangling on disconnect, so dev.driver is + * the reliable "still bound" test under this lock. Use device_trylock() + * to stay off the lockdep chain of the interface being probed and let + * the caller retry via -EPROBE_DEFER if the sibling is momentarily busy. + */ + if (!device_trylock(&sibling_intf->dev)) + return NULL; + if (sibling_intf->dev.driver) { + sibling_hdev = usb_get_intfdata(sibling_intf); + if (sibling_hdev && + sibling_hdev->driver == &steelseries_arctis_driver) { + sd = hid_get_drvdata(sibling_hdev); + if (sd) + kref_get(&sd->refcnt); + } + } + device_unlock(&sibling_intf->dev); + + return sd; +} + static int steelseries_arctis_probe(struct hid_device *hdev, const struct hid_device_id *id) { @@ -339,43 +388,81 @@ static int steelseries_arctis_probe(struct hid_device *hdev, if (ret) return ret; - /* Let hid-generic handle non-sync interfaces */ - if (interface_num != info->sync_interface) + /* Let hid-generic handle non-vendor or unknown interfaces */ + if (interface_num != info->sync_interface && + (!info->async_interface || interface_num != info->async_interface)) return hid_hw_start(hdev, HID_CONNECT_DEFAULT); - sd = kzalloc_obj(*sd, GFP_KERNEL); - if (!sd) - return -ENOMEM; + if (interface_num == info->sync_interface) { + sd = kzalloc_obj(*sd, GFP_KERNEL); + if (!sd) + return -ENOMEM; - kref_init(&sd->refcnt); - sd->hdev = hdev; - sd->info = info; - spin_lock_init(&sd->lock); + kref_init(&sd->refcnt); + sd->hdev = hdev; + sd->info = info; + spin_lock_init(&sd->lock); + INIT_DELAYED_WORK(&sd->status_work, steelseries_status_timer_work_handler); - hid_set_drvdata(hdev, sd); + ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT); + if (ret) + goto err_free; - ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT); - if (ret) - goto err_put; + ret = hid_hw_open(hdev); + if (ret) + goto err_stop; - ret = hid_hw_open(hdev); - if (ret) - goto err_stop; + if (info->capabilities & SS_CAP_BATTERY) { + ret = steelseries_battery_register(sd); + if (ret < 0) + hid_warn(hdev, "Failed to register battery: %d\n", ret); + } - if (info->capabilities & SS_CAP_BATTERY) { - ret = steelseries_battery_register(sd); - if (ret < 0) - hid_warn(hdev, "Failed to register battery: %d\n", ret); + /* + * Publish drvdata only once fully initialised: the async sibling + * attaches by reading it, so it must never observe a half-built or + * failed instance. A failed probe never gets here, so the error + * path below has nothing to unpublish. + */ + hid_set_drvdata(hdev, sd); + schedule_delayed_work(&sd->status_work, msecs_to_jiffies(100)); + + return 0; } - INIT_DELAYED_WORK(&sd->status_work, steelseries_status_timer_work_handler); - schedule_delayed_work(&sd->status_work, msecs_to_jiffies(100)); + /* + * The async interface shares the steelseries_device created by the + * sync interface. Defer until the sync interface has probed and + * published its drvdata. + */ + if (info->async_interface && interface_num == info->async_interface) { + sd = steelseries_get_sibling_sd(hdev, info->sync_interface); + if (!sd) + return -EPROBE_DEFER; - return 0; + hid_set_drvdata(hdev, sd); + + ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT); + if (ret) { + kref_put(&sd->refcnt, steelseries_device_release); + return ret; + } + + ret = hid_hw_open(hdev); + if (ret) { + hid_hw_stop(hdev); + kref_put(&sd->refcnt, steelseries_device_release); + return ret; + } + return 0; + } + + return -ENODEV; err_stop: hid_hw_stop(hdev); -err_put: +err_free: + /* drvdata is unpublished until full success, so no sibling can hold sd. */ kref_put(&sd->refcnt, steelseries_device_release); return ret; } @@ -428,10 +515,21 @@ static int steelseries_arctis_raw_event(struct hid_device *hdev, u8 old_capacity; bool old_connected; bool old_charging; + bool is_async_interface; + unsigned long flags; if (!sd) return 0; + is_async_interface = (hdev != sd->hdev); + + spin_lock_irqsave(&sd->lock, flags); + + if (sd->removed) { + spin_unlock_irqrestore(&sd->lock, flags); + return 0; + } + old_capacity = sd->battery_capacity; old_connected = sd->headset_connected; old_charging = sd->battery_charging; @@ -444,6 +542,10 @@ static int steelseries_arctis_raw_event(struct hid_device *hdev, old_connected ? "" : "not ", sd->headset_connected ? "" : "not "); + if (sd->headset_connected && !old_connected && + sd->info->async_interface && is_async_interface) + schedule_delayed_work(&sd->status_work, 0); + if (sd->battery) { steelseries_headset_set_wireless_status(sd->hdev, sd->headset_connected); @@ -467,6 +569,8 @@ static int steelseries_arctis_raw_event(struct hid_device *hdev, power_supply_changed(sd->battery); } + spin_unlock_irqrestore(&sd->lock, flags); + return 0; }