From nobody Sun Oct 5 18:17:27 2025 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A271B1917F4 for ; Fri, 1 Aug 2025 03:40:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754019647; cv=none; b=Z/RY4cMWenst0xdNIu5BpLAKqyxFu5ohpPGd9qPm92d2qyRiCXMIUN98/4628x3KQYq2SyXtTTGwqeyf9GyQhG0IURYYCeOf7gs72mn4f15Yi7FsMPm5VAEiDlfyOSjxea2HnwTpEumntKUa+VdII7JSezY8PAqGpCTPJjLKoXI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754019647; c=relaxed/simple; bh=b5avWyHXz/1OWZ/aBU1PJnAuPzJmoeYgCrTmNPRbjto=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=QMmqzO7Gc8tCRdqFllpB02uy/TZIHWUBh8kjlhpnyxBb7yBs1z592t1zXYfDzX52JvH5+MZ0Hpau5g6DC+b+xw8Q1yVWeLSiVEoeGDCy2n7EQK71RJz7q/4KsvzAZ8cICI3HGwq+ui3iFgbeFYzdND3PjbepbUv2IePt3NG/D8w= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--guanyulin.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=uEdPt6KK; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--guanyulin.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="uEdPt6KK" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-3132e7266d3so607323a91.2 for ; Thu, 31 Jul 2025 20:40:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1754019645; x=1754624445; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=GWbckXu8w1ij4VqvtPCrxTqcWwxpTgFRcitQcVlE1Os=; b=uEdPt6KKUJi897Ab9q2D3m9xYmJvopjJfeUpW7nMTouRREXTRNocB5vp6MCyDmeAuM Velvzcv75Tc/Iq3gzlD4HgwVUTb6/INUjYXq8TCyvwRElrFMJoApvHe2lIDXpSo8bs3v 5BMC34UFacCKkW8MQN8UWEaxBQGy7c98nehzxjqlEOWCnRPJdUVbZBt2WhvJfLaai3Ex 4y57VsYcxHC9kQP7oma8wWYOnP5C+qTNNQ/Z4/H1sg/RiBawR8F1Mi3KE7KzMh4eYzTL T0LidH5QcPZNy0XOnpmgqSRwquuFR0UbDmv+v4g3ePER4zOYl6QCsvfSy1IAv+kg8jR7 63Fg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1754019645; x=1754624445; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=GWbckXu8w1ij4VqvtPCrxTqcWwxpTgFRcitQcVlE1Os=; b=QccyH2ZZt7/4WNOtu45cm8p+a6zXAfBB/yGktAXq8mNSfmwiVE6J1jaK6prk3WtFQ6 54vzHGajg+4sxz4gb4ftpTrL2MHaTOpbIyYFnZUALX+Omi52YlaeUgtxxRXDTUYDUdM7 ajL3lst6T3H7CtfhX7gkU1pCd6vjQ6Csd7u7Grk+Pp/Zt16A5Yvr29nzAozXbUjilhVT YK5DQet+ftLDdUYFoyk8pvCtPBrgMMmcUf3w+Wce7QgsqVus4E4/B2KXQAw/bhS6WdBG fQQInVqUInanAJDt5FTMqLf3KncAJ7Im4R4pwzqg7FmBHsw2ahPzTMiG1oF6nIzR4nL0 9hPw== X-Forwarded-Encrypted: i=1; AJvYcCV4SaVv0P5ZXDKmejK4IwGeMoZWMvXgUhtZY86ZrhGKEUrwEw8eeHDbWBMDKywHrRJQaHm5LU3A1nYPfpQ=@vger.kernel.org X-Gm-Message-State: AOJu0YzP9bDe1WFmzdPlvQzFaWd4/fDCE+Xa8NX/WuLrV2ppoP4XYAQI xpR8ywhSgI/eqbgxjsMOaQuvvQsMapWRksWt5EXqmw0/GoLjzFSAWraUx9QSmrMe/b8NJeS6sav ucIot38VGzB0iIz4LVw== X-Google-Smtp-Source: AGHT+IH7gXP7DQrgws2wF/AzNXCxPAonzRIhflG+PxSPkDwmJiEggxfBi0vCz7RLILsIFXU65hTeWtGUPLYMcuU= X-Received: from pjbqo6.prod.google.com ([2002:a17:90b:3dc6:b0:311:ff0f:6962]) (user=guanyulin job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:3c4f:b0:31f:e6e:7313 with SMTP id 98e67ed59e1d1-31f5dd6fd4cmr13217443a91.3.1754019644947; Thu, 31 Jul 2025 20:40:44 -0700 (PDT) Date: Fri, 1 Aug 2025 03:39:31 +0000 In-Reply-To: <20250801034004.3314737-1-guanyulin@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250801034004.3314737-1-guanyulin@google.com> X-Mailer: git-send-email 2.50.1.565.gc32cd1483b-goog Message-ID: <20250801034004.3314737-3-guanyulin@google.com> Subject: [PATCH v15 2/4] usb: offload: add apis for offload usage tracking From: Guan-Yu Lin To: gregkh@linuxfoundation.org, mathias.nyman@intel.com, hannelotta@gmail.com, zijun.hu@oss.qualcomm.com, xu.yang_2@nxp.com, stern@rowland.harvard.edu, andriy.shevchenko@linux.intel.com, ben@decadent.org.uk, quic_wcheng@quicinc.com, krzysztof.kozlowski@linaro.org, dh10.jung@samsung.com Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Guan-Yu Lin Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Introduce offload_usage and corresponding apis to track offload usage on each USB device. Offload denotes that there is another co-processor accessing the USB device via the same USB host controller. To optimize power usage, it's essential to monitor whether the USB device is actively used by other co-processor. This information is vital when determining if a USB device can be safely suspended during system power state transitions. Signed-off-by: Guan-Yu Lin --- drivers/usb/core/Kconfig | 10 +++ drivers/usb/core/Makefile | 1 + drivers/usb/core/offload.c | 136 +++++++++++++++++++++++++++++++++++++ drivers/usb/core/usb.c | 1 + include/linux/usb.h | 18 +++++ 5 files changed, 166 insertions(+) create mode 100644 drivers/usb/core/offload.c diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig index 58e3ca7e4793..d5d38657f929 100644 --- a/drivers/usb/core/Kconfig +++ b/drivers/usb/core/Kconfig @@ -143,3 +143,13 @@ config USB_DEFAULT_AUTHORIZATION_MODE ACPI selecting value 2 is analogous to selecting value 0. =20 If unsure, keep the default value. + +config USB_OFFLOAD + bool "Enable USB offload feature" + depends on USB + depends on USB_XHCI_SIDEBAND_SUSPEND + help + Offload denotes that there is another co-processor accessing the + USB device via the same USB host controller, creating the + "offloaded USB transfers". Say Y to allow offloaded USB + transfers during system sleep (Suspend-to-RAM). diff --git a/drivers/usb/core/Makefile b/drivers/usb/core/Makefile index ac006abd13b3..df26c2885dd8 100644 --- a/drivers/usb/core/Makefile +++ b/drivers/usb/core/Makefile @@ -9,6 +9,7 @@ usbcore-y +=3D devio.o notify.o generic.o quirks.o devices.o usbcore-y +=3D phy.o port.o =20 usbcore-$(CONFIG_OF) +=3D of.o +usbcore-$(CONFIG_USB_OFFLOAD) +=3D offload.o usbcore-$(CONFIG_USB_PCI) +=3D hcd-pci.o usbcore-$(CONFIG_ACPI) +=3D usb-acpi.o =20 diff --git a/drivers/usb/core/offload.c b/drivers/usb/core/offload.c new file mode 100644 index 000000000000..7c699f1b8d2b --- /dev/null +++ b/drivers/usb/core/offload.c @@ -0,0 +1,136 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * offload.c - USB offload related functions + * + * Copyright (c) 2025, Google LLC. + * + * Author: Guan-Yu Lin + */ + +#include + +#include "usb.h" + +/** + * usb_offload_get - increment the offload_usage of a USB device + * @udev: the USB device to increment its offload_usage + * + * Incrementing the offload_usage of a usb_device indicates that offload is + * enabled on this usb_device; that is, another entity is actively handlin= g USB + * transfers. This information allows the USB driver to adjust its power + * management policy based on offload activity. + * + * Return: 0 on success. A negative error code otherwise. + */ +int usb_offload_get(struct usb_device *udev) +{ + int ret; + + usb_lock_device(udev); + if (udev->state =3D=3D USB_STATE_NOTATTACHED) { + usb_unlock_device(udev); + return -ENODEV; + } + + if (udev->state =3D=3D USB_STATE_SUSPENDED || + udev->offload_at_suspend) { + usb_unlock_device(udev); + return -EBUSY; + } + + /* + * offload_usage could only be modified when the device is active, since + * it will alter the suspend flow of the device. + */ + ret =3D usb_autoresume_device(udev); + if (ret < 0) { + usb_unlock_device(udev); + return ret; + } + + udev->offload_usage++; + usb_autosuspend_device(udev); + usb_unlock_device(udev); + + return ret; +} +EXPORT_SYMBOL_GPL(usb_offload_get); + +/** + * usb_offload_put - drop the offload_usage of a USB device + * @udev: the USB device to drop its offload_usage + * + * The inverse operation of usb_offload_get, which drops the offload_usage= of + * a USB device. This information allows the USB driver to adjust its power + * management policy based on offload activity. + * + * Return: 0 on success. A negative error code otherwise. + */ +int usb_offload_put(struct usb_device *udev) +{ + int ret; + + usb_lock_device(udev); + if (udev->state =3D=3D USB_STATE_NOTATTACHED) { + usb_unlock_device(udev); + return -ENODEV; + } + + if (udev->state =3D=3D USB_STATE_SUSPENDED || + udev->offload_at_suspend) { + usb_unlock_device(udev); + return -EBUSY; + } + + /* + * offload_usage could only be modified when the device is active, since + * it will alter the suspend flow of the device. + */ + ret =3D usb_autoresume_device(udev); + if (ret < 0) { + usb_unlock_device(udev); + return ret; + } + + /* Drop the count when it wasn't 0, ignore the operation otherwise. */ + if (udev->offload_usage) + udev->offload_usage--; + usb_autosuspend_device(udev); + usb_unlock_device(udev); + + return ret; +} +EXPORT_SYMBOL_GPL(usb_offload_put); + +/** + * usb_offload_check - check offload activities on a USB device + * @udev: the USB device to check its offload activity. + * + * Check if there are any offload activity on the USB device right now. Th= is + * information could be used for power management or other forms of resour= ce + * management. + * + * The caller must hold @udev's device lock. In addition, the caller should + * ensure downstream usb devices are all either suspended or marked as + * "offload_at_suspend" to ensure the correctness of the return value. + * + * Returns true on any offload activity, false otherwise. + */ +bool usb_offload_check(struct usb_device *udev) __must_hold(&udev->dev->mu= tex) +{ + struct usb_device *child; + bool active; + int port1; + + usb_hub_for_each_child(udev, port1, child) { + usb_lock_device(child); + active =3D usb_offload_check(child); + usb_unlock_device(child); + if (active) + return true; + } + + return !!udev->offload_usage; +} +EXPORT_SYMBOL_GPL(usb_offload_check); diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c index fca7735fc660..e6b9ab8b4a34 100644 --- a/drivers/usb/core/usb.c +++ b/drivers/usb/core/usb.c @@ -670,6 +670,7 @@ struct usb_device *usb_alloc_dev(struct usb_device *par= ent, set_dev_node(&dev->dev, dev_to_node(bus->sysdev)); dev->state =3D USB_STATE_ATTACHED; dev->lpm_disable_count =3D 1; + dev->offload_usage =3D 0; atomic_set(&dev->urbnum, 0); =20 INIT_LIST_HEAD(&dev->ep0.urb_list); diff --git a/include/linux/usb.h b/include/linux/usb.h index 9d662c6abb4d..81fc0d93783f 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -636,6 +636,8 @@ struct usb3_lpm_parameters { * @do_remote_wakeup: remote wakeup should be enabled * @reset_resume: needs reset instead of resume * @port_is_suspended: the upstream port is suspended (L2 or U3) + * @offload_at_suspend: offload activities during suspend is enabled. + * @offload_usage: number of offload activities happening on this usb devi= ce. * @slot_id: Slot ID assigned by xHCI * @l1_params: best effor service latency for USB2 L1 LPM state, and L1 ti= meout. * @u1_params: exit latencies for USB3 U1 LPM state, and hub-initiated tim= eout. @@ -724,6 +726,8 @@ struct usb_device { unsigned do_remote_wakeup:1; unsigned reset_resume:1; unsigned port_is_suspended:1; + unsigned offload_at_suspend:1; + int offload_usage; enum usb_link_tunnel_mode tunnel_mode; struct device_link *usb4_link; =20 @@ -841,6 +845,20 @@ static inline void usb_mark_last_busy(struct usb_devic= e *udev) { } #endif =20 +#if IS_ENABLED(CONFIG_USB_OFFLOAD) +int usb_offload_get(struct usb_device *udev); +int usb_offload_put(struct usb_device *udev); +bool usb_offload_check(struct usb_device *udev); +#else + +static inline int usb_offload_get(struct usb_device *udev) +{ return 0; } +static inline int usb_offload_put(struct usb_device *udev) +{ return 0; } +static inline bool usb_offload_check(struct usb_device *udev) +{ return false; } +#endif + extern int usb_disable_lpm(struct usb_device *udev); extern void usb_enable_lpm(struct usb_device *udev); /* Same as above, but these functions lock/unlock the bandwidth_mutex. */ --=20 2.50.1.565.gc32cd1483b-goog