From mboxrd@z Thu Jan 1 00:00:00 1970 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 D911DC433E0 for ; Mon, 18 Jan 2021 17:18:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD21922C7E for ; Mon, 18 Jan 2021 17:18:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406934AbhARRSn (ORCPT ); Mon, 18 Jan 2021 12:18:43 -0500 Received: from out3-smtp.messagingengine.com ([66.111.4.27]:36833 "EHLO out3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406908AbhARRS2 (ORCPT ); Mon, 18 Jan 2021 12:18:28 -0500 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailout.nyi.internal (Postfix) with ESMTP id 04CAE5C00CF; Mon, 18 Jan 2021 12:17:19 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute4.internal (MEProxy); Mon, 18 Jan 2021 12:17:19 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kroah.com; h= date:from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=fm2; bh=I7PuudX5NIkn1LEPg0h00j6g658 gCi7iltCAsy0R/yA=; b=hJIZXbAriNodKHjDtQPLj8rq+1CoCTD1QIccwMcBAvF 8HKmbnj4hy8uIMgmJiz1mg0pZ0+A2KdzxOEE1sk4ZhTtaRh/M8bntEVzYPXjgEYP ah+7x8id2SvcP9GDDlGqpbyG1trlgy0FkZixu5Fj0DvLyQxqHx3pFRLXepCiyW3F SuW7TuUSMl/NCdk2XTXw1BHfniu5MOrO125SWq/jawL6L56twcNnwq8Dl+AHeb0h kFZfjKcrtREkATLNFspCbjSLb86smuXk81mrwti6zOv4Zwu0OUF7GqPpElpV+XGt kAg0UWFvLLgmXwJOMF3R5uTtRGf5ARY3nKtNiM9Hh0g== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm1; bh=I7Puud X5NIkn1LEPg0h00j6g658gCi7iltCAsy0R/yA=; b=TTjLIuuEvZrR23XX2mjt/M JJ3W6HkCpU0h+3FAIwpE0k6XoTxOCovXMjgWD92nMmljGcmuSbOtqP/aiWa1W+9q Cfoqs4eWZWhU0/PKxSclWMi3ywXyBueGPGoPfqWfcRrihf+CeU5qa/ymcrAwuc6S lNIealO8aqT9TYA/wT0VDcFrO/uAjxpt62+gVPtk/DlRyzAA6zsNXKai+bL+UT6N E3dBmRXuTUSO3z4vKmFaqpdVnFSsiU0BJP/skdqBDXXjzI80C5Q1Iz5dPyI3eAm/ 3Iif6Tq2G7Fap8oS2oiG7c3YhRGnWSHBG8ASFzB+EowApeTxoQf3+p5+3qnkqX+g == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrtdekgddutddtucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvffukfhfgggtuggjsehttdertddttddvnecuhfhrohhmpefirhgvghcu mffjuceoghhrvghgsehkrhhorghhrdgtohhmqeenucggtffrrghtthgvrhhnpeevueehje fgfffgiedvudekvdektdelleelgefhleejieeugeegveeuuddukedvteenucfkphepkeef rdekiedrjeegrdeigeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrih hlfhhrohhmpehgrhgvgheskhhrohgrhhdrtghomh X-ME-Proxy: Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) by mail.messagingengine.com (Postfix) with ESMTPA id 4525B1080057; Mon, 18 Jan 2021 12:17:17 -0500 (EST) Date: Mon, 18 Jan 2021 18:17:16 +0100 From: Greg KH To: Lukasz Luba Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, cw00.choi@samsung.com, myungjoo.ham@samsung.com, kyungmin.park@samsung.com Subject: Re: [PATCH] PM / devfreq: Add sysfs attributes to simple_ondemand governor Message-ID: References: <20210115170530.22603-1-lukasz.luba@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210115170530.22603-1-lukasz.luba@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Fri, Jan 15, 2021 at 05:05:30PM +0000, Lukasz Luba wrote: > The simple_ondemand devfreq governor is used by quite a few devices, like > GPUs, DSPs, memory controllers, etc. It implements algorithm which tries > to predict the device frequency based on past statistics. There are two > tunables for the algorithm: 'upthreshold' and 'downdifferential'. These > tunables change the behavior of the decision, e.g. how fast to increase > the frequency or how rapidly limit the frequency. These values might be > different based on the application which is currently running, e.g. > different behavior is needed for a game than for web browsing or clean > desktop. The patch exports these two tunables so they can be adjusted > based on current need. There is also a check with the allowed ranges > to make sure the values are correct and safe. > > Signed-off-by: Lukasz Luba > --- > drivers/devfreq/governor_simpleondemand.c | 135 ++++++++++++++++++++++ > 1 file changed, 135 insertions(+) > > diff --git a/drivers/devfreq/governor_simpleondemand.c b/drivers/devfreq/governor_simpleondemand.c > index d57b82a2b570..4b3c182e0a49 100644 > --- a/drivers/devfreq/governor_simpleondemand.c > +++ b/drivers/devfreq/governor_simpleondemand.c > @@ -15,6 +15,7 @@ > /* Default constants for DevFreq-Simple-Ondemand (DFSO) */ > #define DFSO_UPTHRESHOLD (90) > #define DFSO_DOWNDIFFERENCTIAL (5) > +#define DFSO_MAX_VALUE (100) > static int devfreq_simple_ondemand_func(struct devfreq *df, > unsigned long *freq) > { > @@ -84,15 +85,149 @@ static int devfreq_simple_ondemand_func(struct devfreq *df, > return 0; > } > > +static ssize_t upthreshold_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct devfreq_simple_ondemand_data *data; > + struct devfreq *df = to_devfreq(dev); > + > + if (!df->data) > + return -EINVAL; > + > + data = df->data; > + > + return sprintf(buf, "%d\n", data->upthreshold); sysfs_emit()? Also, you forgot the Documentation/ABI/ updates for new sysfs files :( > +} > + > +static ssize_t upthreshold_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t count) > +{ > + struct devfreq_simple_ondemand_data *data; > + struct devfreq *df = to_devfreq(dev); > + unsigned int value; > + int ret; > + > + if (!df->data) > + return -EINVAL; > + > + data = df->data; > + > + ret = kstrtouint(buf, 10, &value); > + if (ret < 0) > + return -EINVAL; > + > + mutex_lock(&df->lock); > + > + if (value > DFSO_MAX_VALUE || value <= data->downdifferential) { > + mutex_unlock(&df->lock); > + return -EINVAL; > + } > + > + data->upthreshold = value; > + mutex_unlock(&df->lock); > + > + return count; > +} > +static DEVICE_ATTR_RW(upthreshold); > + > +static ssize_t downdifferential_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct devfreq_simple_ondemand_data *data; > + struct devfreq *df = to_devfreq(dev); > + > + if (!df->data) > + return -EINVAL; > + > + data = df->data; > + > + return sprintf(buf, "%d\n", data->downdifferential); > +} > + > +static ssize_t downdifferential_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, size_t count) > +{ > + struct devfreq_simple_ondemand_data *data; > + struct devfreq *df = to_devfreq(dev); > + unsigned int value; > + int ret; > + > + if (!df->data) > + return -EINVAL; > + > + data = df->data; > + > + ret = kstrtouint(buf, 10, &value); > + if (ret < 0) > + return -EINVAL; > + > + mutex_lock(&df->lock); > + > + if (value > DFSO_MAX_VALUE || value >= data->upthreshold) { > + mutex_unlock(&df->lock); > + return -EINVAL; > + } > + > + data->downdifferential = value; > + mutex_unlock(&df->lock); > + > + return count; > +} > +static DEVICE_ATTR_RW(downdifferential); > + > +static void devfreq_simple_ondemand_sysfs_setup(struct devfreq *df) > +{ > + struct devfreq_simple_ondemand_data *data; > + int ret; > + > + if (!df->data) { > + /* The memory will be freed automatically */ > + df->data = devm_kzalloc(&df->dev, > + sizeof(struct devfreq_simple_ondemand_data), > + GFP_KERNEL); > + if (!df->data) { > + dev_warn(&df->dev, "Unable to allocate memory"); > + return; > + } > + } > + > + data = df->data; > + > + /* After new allocation setup default values, since they are used */ > + if (!data->upthreshold) > + data->upthreshold = DFSO_UPTHRESHOLD; > + > + if (!data->downdifferential) > + data->downdifferential = DFSO_DOWNDIFFERENCTIAL; > + > + ret = sysfs_create_file(&df->dev.kobj, &dev_attr_upthreshold.attr); > + if (ret < 0) > + dev_warn(&df->dev, "Unable to create 'upthreshold' attr\n"); > + > + ret = sysfs_create_file(&df->dev.kobj, &dev_attr_downdifferential.attr); > + if (ret < 0) > + dev_warn(&df->dev, "Unable to create 'downdifferential' attr\n"); You just raced with userspace and lost :( Please use the default sysfs groups so that it all works properly. Huge hint, when calling sysfs_* from a driver, that usually means you are doing something wrong. thanks, greg k-h