From patchwork Thu Oct 15 19:38:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lina Iyer X-Patchwork-Id: 286779 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B2C5C43457 for ; Thu, 15 Oct 2020 19:38:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E6BBE206E5 for ; Thu, 15 Oct 2020 19:38:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="VR+3I2bH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391793AbgJOTiR (ORCPT ); Thu, 15 Oct 2020 15:38:17 -0400 Received: from m42-4.mailgun.net ([69.72.42.4]:17648 "EHLO m42-4.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391788AbgJOTiR (ORCPT ); Thu, 15 Oct 2020 15:38:17 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1602790695; h=Content-Transfer-Encoding: MIME-Version: References: In-Reply-To: Message-Id: Date: Subject: Cc: To: From: Sender; bh=+7QBCxKGdejB03bZtuAiEQh1dYEk8xx/JcoCbYRQQOk=; b=VR+3I2bHxqF9eIOyqy/493IChmcPTaFAmexJ3uE9Lkfxgb2nBFF/vLbbaSkgsvMUcIN3XjZb gPy683gWV9Qy132kEtY0Xb2mgmL/Gk3mturIEmPhUz9E6odthau+HttiB498x4CdYQXtoEcz 6aL9iPTTlu/9UKuurBx/t5eyVIU= X-Mailgun-Sending-Ip: 69.72.42.4 X-Mailgun-Sid: WyI5ZDFmMiIsICJsaW51eC1wbUB2Z2VyLmtlcm5lbC5vcmciLCAiYmU5ZTRhIl0= Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n04.prod.us-west-2.postgun.com with SMTP id 5f88a526d6d00c7a9ea86815 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Thu, 15 Oct 2020 19:38:14 GMT Sender: ilina=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 84094C43387; Thu, 15 Oct 2020 19:38:14 +0000 (UTC) Received: from codeaurora.org (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: ilina) by smtp.codeaurora.org (Postfix) with ESMTPSA id 79DEAC433FF; Thu, 15 Oct 2020 19:38:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 79DEAC433FF Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=ilina@codeaurora.org From: Lina Iyer To: rjw@rjwysocki.net, ulf.hansson@linaro.org, linux-pm@vger.kernel.org Cc: linux-arm-msm@vger.kernel.org, Lina Iyer Subject: [PATCH v3 1/2] PM / runtime: inform runtime PM of a device's next wakeup Date: Thu, 15 Oct 2020 13:38:06 -0600 Message-Id: <20201015193807.17423-2-ilina@codeaurora.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201015193807.17423-1-ilina@codeaurora.org> References: <20201015193807.17423-1-ilina@codeaurora.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Some devices may have a predictable interrupt pattern while executing usecases. An example would be the VSYNC interrupt associated with display devices. A 60 Hz display could cause a interrupt every 16 ms. If the device were in a PM domain, the domain would need to be powered up for device to resume and handle the interrupt. Entering a domain idle state saves power, only if the residency of the idle state is met. Without knowing the idle duration of the domain, the governor would just choose the deepest idle state that matches the QoS requirements. The domain might be powered off just as the device is expecting to wake up. If devices could inform runtime PM of their next event, the parent PM domain's idle duration can be determined. So let's add the pm_runtime_set_next_wake() API for the device to notify runtime PM of the impending wakeup and document it's usage. Signed-off-by: Lina Iyer --- Changes in v2: - Update documentation - Remove runtime PM enabled check - Update commit text --- Documentation/power/runtime_pm.rst | 17 +++++++++++++++++ drivers/base/power/runtime.c | 24 ++++++++++++++++++++++++ include/linux/pm.h | 2 ++ include/linux/pm_runtime.h | 1 + 4 files changed, 44 insertions(+) diff --git a/Documentation/power/runtime_pm.rst b/Documentation/power/runtime_pm.rst index 0553008b6279..f6aaef15a511 100644 --- a/Documentation/power/runtime_pm.rst +++ b/Documentation/power/runtime_pm.rst @@ -515,6 +515,12 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: power.use_autosuspend isn't set, otherwise returns the expiration time in jiffies + `int pm_runtime_set_next_event(struct device *dev, ktime_t next);` + - inform runtime PM of the next event on the device. Devices that are + sensitive to their domain idle enter/exit latencies may provide this + information for use by the PM domain governor. The domain governor would + use this information to calculate it's sleep length. + It is safe to execute the following helper functions from interrupt context: - pm_request_idle() @@ -545,6 +551,7 @@ functions may also be used in interrupt context: - pm_runtime_put_sync() - pm_runtime_put_sync_suspend() - pm_runtime_put_sync_autosuspend() +- pm_runtime_set_next_event() 5. Runtime PM Initialization, Device Probing and Removal ======================================================== @@ -639,6 +646,16 @@ suspend routine). It may be necessary to resume the device and suspend it again in order to do so. The same is true if the driver uses different power levels or other settings for runtime suspend and system sleep. +When a device enters idle at runtime, it may trigger the runtime PM up the +hierarchy and if device has a predictable interrupt pattern, we can even do a +better job at determining the parent's idle state. For example, a display +device gets a VSYNC interrupt every 16 ms when running at 60 Hz. When it's PM +domain is powering down and happens to be at the boundary of the VSYNC +interrupt, it may not be efficient to power off the domain. Knowing the next +wake up (when available) for devices in the domain we can determine the idle +duration of the domain. By comparing idle duration with the residencies of the +domain idle states, we can be efficient in both power and performance. + During system resume, the simplest approach is to bring all devices back to full power, even if they had been suspended before the system suspend began. There are several reasons for this, including: diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index 8143210a5c54..5d2ebacfd35e 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -122,6 +122,27 @@ u64 pm_runtime_suspended_time(struct device *dev) } EXPORT_SYMBOL_GPL(pm_runtime_suspended_time); +/** + * pm_runtime_set_next_wakeup_event - Notify PM framework of an impending event. + * @dev: Device to handle + * @next: impending interrupt/wakeup for the device + */ +int pm_runtime_set_next_event(struct device *dev, ktime_t next) +{ + unsigned long flags; + int ret = -EINVAL; + + spin_lock_irqsave(&dev->power.lock, flags); + if (ktime_before(ktime_get(), next)) { + dev->power.next_event = next; + ret = 0; + } + spin_unlock_irqrestore(&dev->power.lock, flags); + + return ret; +} +EXPORT_SYMBOL_GPL(pm_runtime_set_next_event); + /** * pm_runtime_deactivate_timer - Deactivate given device's suspend timer. * @dev: Device to handle. @@ -1415,6 +1436,9 @@ void pm_runtime_enable(struct device *dev) "Enabling runtime PM for inactive device (%s) with active children\n", dev_name(dev)); + /* Reset the next wakeup for the device */ + dev->power.next_event = KTIME_MAX; + spin_unlock_irqrestore(&dev->power.lock, flags); } EXPORT_SYMBOL_GPL(pm_runtime_enable); diff --git a/include/linux/pm.h b/include/linux/pm.h index a30a4b54df52..9051658674a4 100644 --- a/include/linux/pm.h +++ b/include/linux/pm.h @@ -8,6 +8,7 @@ #ifndef _LINUX_PM_H #define _LINUX_PM_H +#include #include #include #include @@ -616,6 +617,7 @@ struct dev_pm_info { u64 active_time; u64 suspended_time; u64 accounting_timestamp; + ktime_t next_event; #endif struct pm_subsys_data *subsys_data; /* Owned by the subsystem. */ void (*set_latency_tolerance)(struct device *, s32); diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h index 6245caa18034..af6d35178335 100644 --- a/include/linux/pm_runtime.h +++ b/include/linux/pm_runtime.h @@ -59,6 +59,7 @@ extern void pm_runtime_get_suppliers(struct device *dev); extern void pm_runtime_put_suppliers(struct device *dev); extern void pm_runtime_new_link(struct device *dev); extern void pm_runtime_drop_link(struct device *dev); +extern int pm_runtime_set_next_event(struct device *dev, ktime_t next); /** * pm_runtime_get_if_in_use - Conditionally bump up runtime PM usage counter.