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Fri, 6 Dec 2019 11:32:18 +0900 (KST) Received: from [10.113.221.102] (unknown [10.113.221.102]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20191206023218epsmtip1e9c48596faaba27e5d1ca19b645809d2~dp262nUs90041300413epsmtip1l; Fri, 6 Dec 2019 02:32:18 +0000 (GMT) Subject: Re: [PATCH v2 2/2] PM / devfreq: Use PM QoS for sysfs min/max_freq To: Matthias Kaehlcke , Leonard Crestez From: Chanwoo Choi Organization: Samsung Electronics Message-ID: <129c11ff-f808-654e-d571-6248c887c973@samsung.com> Date: Fri, 6 Dec 2019 11:38:31 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:59.0) Gecko/20100101 Thunderbird/59.0 MIME-Version: 1.0 In-Reply-To: <20191205180253.GN228856@google.com> Content-Language: en-US X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrFJsWRmVeSWpSXmKPExsWy7bCmru7mvS9jDf5e4rU4dGwru8X0vZvY LM42vWG3WHH3I6vFpsfXWC26fq1ktvjce4TR4vOGx4wWtxtXsFmsPneQzeLM6UusFhu/ejjw eMxuuMjicefaHjaPzUvqPTa+28HkcfDdHiaPLVfbWTz6tqxi9Pi8SS6AIyrbJiM1MSW1SCE1 Lzk/JTMv3VbJOzjeOd7UzMBQ19DSwlxJIS8xN9VWycUnQNctMwfoWCWFssScUqBQQGJxsZK+ nU1RfmlJqkJGfnGJrVJqQUpOgWWBXnFibnFpXrpecn6ulaGBgZEpUGFCdsbsR4uYC3aoV2y8 epe9gXGmQhcjJ4eEgInEqg/XWbsYuTiEBHYwSmzrO8cO4XxilPh97DIbhPONUWLyssksMC0P n35gBbGFBPYySpybWgtR9J5RouPQfMYuRg4OYQFvie6V/iA1IgKhEr1bv7OA1DALzGOW6Fp3 hxEkwSagJbH/xQ02EJtfQFHi6o/HYHFeATuJ1u4JYHEWARWJ65c/M4HYogJhEie3tUDVCEqc nPkE7CBOAUOJy+dmsIPYzALiEreezGeCsOUltr+dwwyyWEJgE7vEkb/T2ECOkxBwkbi8KBzi GWGJV8e3sEPYUhIv+9ug7GqJlSePsEH0djBKbNl/gRUiYSyxf+lkJpA5zAKaEut36UOEFSV2 /p7LCLGXT+Ld1x5WiFW8Eh1tQhAlyhKXH9xlgrAlJRa3d7JNYFSaheSbWUg+mIXkg1kIyxYw sqxiFEstKM5NTy02LDBBjuxNjOB0rGWxg3HPOZ9DjAIcjEo8vDM+v4gVYk0sK67MPcQowcGs JMKbzvcyVog3JbGyKrUoP76oNCe1+BCjKTCwJzJLiSbnA3NFXkm8oamRsbGxhYmhmamhoZI4 L8ePi7FCAumJJanZqakFqUUwfUwcnFINjLE6gRs6xIxVq33/Hbj3JCb7msXUu4pnJ2Xldyh+ sLzwPtVQOodLVNDm+o2t+hPWZmilmn0tL9S+I6dgEB16KvVHqWDLLpPM56kiMiucA+U+hi2q dz4mIlNQmufE+az4Tcqulw4zezfPec4ygyd90Wq59HVC0t9LSnzYRQ/Xc1UZ3n3I7NqgxFKc kWioxVxUnAgAEjf0090DAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrKIsWRmVeSWpSXmKPExsWy7bCSnO6mvS9jDRr69S0OHdvKbjF97yY2 i7NNb9gtVtz9yGqx6fE1VouuXyuZLT73HmG0+LzhMaPF7cYVbBarzx1kszhz+hKrxcavHg48 HrMbLrJ43Lm2h81j85J6j43vdjB5HHy3h8ljy9V2Fo++LasYPT5vkgvgiOKySUnNySxLLdK3 S+DKmP1oEXPBDvWKjVfvsjcwzlToYuTkkBAwkXj49ANrFyMXh5DAbkaJqdfbmCASkhLTLh5l 7mLkALKFJQ4fLoaoecsoMWvDHiaQuLCAt0T3Sn+QchGBUInP/RvZQWqYBRYwS0y/cZQVJCEk 0MkkseqYBojNJqAlsf/FDTYQm19AUeLqj8eMIDavgJ1Ea/cEsDiLgIrE9cufwW4QFQiT2Lnk MRNEjaDEyZlPWEBsTgFDicvnZrCD2MwC6hJ/5l1ihrDFJW49mc8EYctLbH87h3kCo/AsJO2z kLTMQtIyC0nLAkaWVYySqQXFuem5xYYFhnmp5XrFibnFpXnpesn5uZsYwZGppbmD8fKS+EOM AhyMSjy8Mz6/iBViTSwrrsw9xCjBwawkwpvO9zJWiDclsbIqtSg/vqg0J7X4EKM0B4uSOO/T vGORQgLpiSWp2ampBalFMFkmDk6pBsYJDG/Dwpubv/+sr8iUL5BetWuJ+fdz7m41B7RbH3I/ eZh9wenUB4GSyedfb9Eo5vGfKyweli8ddEvqolNjmWNl3B2Buo7mKa0X57DV6pjo/025OFHy S9ezSSd2alWvq529p1pcxi5me6PJssV8/4O//dmdIW1fHFx5uyTS/dxHIdf2zdN1TyqxFGck GmoxFxUnAgD+2cWYyAIAAA== X-CMS-MailID: 20191206023218epcas1p4a433888be987b966a73de814c736f47e X-Msg-Generator: CA X-Sendblock-Type: SVC_REQ_APPROVE CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20191205180259epcas4p3cf54efb95fc13f55b79c1e27c9a9ae0c References: <2b9eeb4e576c45269c01826f13c7811b876faa57.1575540224.git.leonard.crestez@nxp.com> <20191205180253.GN228856@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191205_183234_095105_FF2ED7B4 X-CRM114-Status: GOOD ( 24.21 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?B?QXJ0dXIgxZp3aWdvxYQ=?= , Jacky Bai , linux-pm@vger.kernel.org, Viresh Kumar , "Rafael J. Wysocki" , Kyungmin Park , MyungJoo Ham , NXP Linux Team , Georgi Djakov , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 12/6/19 3:02 AM, Matthias Kaehlcke wrote: > On Thu, Dec 05, 2019 at 12:05:07PM +0200, Leonard Crestez wrote: >> Switch the handling of min_freq and max_freq from sysfs to use the >> dev_pm_qos_request interface. >> >> Since PM QoS handles frequencies as kHz this change reduces the >> precision of min_freq and max_freq. This shouldn't introduce problems >> because frequencies which are not an integer number of kHz are likely >> not an integer number of Hz either. >> >> Try to ensure compatibility by rounding min values down and rounding >> max values up. >> >> Signed-off-by: Leonard Crestez >> Acked-by: Chanwoo Choi >> --- >> drivers/devfreq/devfreq.c | 76 ++++++++++++++++++++++++++++++--------- >> include/linux/devfreq.h | 9 ++--- >> 2 files changed, 64 insertions(+), 21 deletions(-) >> >> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c >> index e8b943fc4259..bcb286509547 100644 >> --- a/drivers/devfreq/devfreq.c >> +++ b/drivers/devfreq/devfreq.c >> @@ -139,14 +139,10 @@ static void get_freq_range(struct devfreq *devfreq, >> *min_freq = max(*min_freq, (unsigned long)HZ_PER_KHZ * qos_min_freq); >> if (qos_max_freq != PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE) >> *max_freq = min(*max_freq, >> (unsigned long)HZ_PER_KHZ * qos_max_freq); >> >> - /* Apply constraints from sysfs */ >> - *min_freq = max(*min_freq, devfreq->min_freq); >> - *max_freq = min(*max_freq, devfreq->max_freq); >> - >> /* Apply constraints from OPP interface */ >> *min_freq = max(*min_freq, devfreq->scaling_min_freq); >> *max_freq = min(*max_freq, devfreq->scaling_max_freq); >> >> if (*min_freq > *max_freq) >> @@ -703,10 +699,23 @@ static void devfreq_dev_release(struct device *dev) >> DEV_PM_QOS_MIN_FREQUENCY); >> if (err && err != -ENOENT) >> dev_warn(dev->parent, >> "Failed to remove min_freq notifier: %d\n", err); >> >> + if (dev_pm_qos_request_active(&devfreq->user_max_freq_req)) { >> + err = dev_pm_qos_remove_request(&devfreq->user_max_freq_req); >> + if (err) >> + dev_warn(dev->parent, >> + "Failed to remove max_freq request: %d\n", err); >> + } >> + if (dev_pm_qos_request_active(&devfreq->user_min_freq_req)) { >> + err = dev_pm_qos_remove_request(&devfreq->user_min_freq_req); >> + if (err) >> + dev_warn(dev->parent, >> + "Failed to remove min_freq request: %d\n", err); >> + } >> + >> if (devfreq->profile->exit) >> devfreq->profile->exit(devfreq->dev.parent); >> >> mutex_destroy(&devfreq->lock); >> kfree(devfreq); >> @@ -776,19 +785,17 @@ struct devfreq *devfreq_add_device(struct device *dev, >> if (!devfreq->scaling_min_freq) { >> mutex_unlock(&devfreq->lock); >> err = -EINVAL; >> goto err_dev; >> } >> - devfreq->min_freq = devfreq->scaling_min_freq; >> >> devfreq->scaling_max_freq = find_available_max_freq(devfreq); >> if (!devfreq->scaling_max_freq) { >> mutex_unlock(&devfreq->lock); >> err = -EINVAL; >> goto err_dev; >> } >> - devfreq->max_freq = devfreq->scaling_max_freq; >> >> devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev); >> atomic_set(&devfreq->suspend_count, 0); >> >> dev_set_name(&devfreq->dev, "devfreq%d", >> @@ -825,10 +832,20 @@ struct devfreq *devfreq_add_device(struct device *dev, >> >> srcu_init_notifier_head(&devfreq->transition_notifier_list); >> >> mutex_unlock(&devfreq->lock); >> >> + err = dev_pm_qos_add_request(dev, &devfreq->user_min_freq_req, >> + DEV_PM_QOS_MIN_FREQUENCY, 0); >> + if (err < 0) >> + goto err_devfreq; >> + err = dev_pm_qos_add_request(dev, &devfreq->user_max_freq_req, >> + DEV_PM_QOS_MAX_FREQUENCY, >> + PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE); >> + if (err < 0) >> + goto err_devfreq; >> + >> devfreq->nb_min.notifier_call = qos_min_notifier_call; >> err = dev_pm_qos_add_notifier(devfreq->dev.parent, &devfreq->nb_min, >> DEV_PM_QOS_MIN_FREQUENCY); >> if (err) >> goto err_devfreq; >> @@ -1418,18 +1435,26 @@ static ssize_t min_freq_store(struct device *dev, struct device_attribute *attr, >> { >> struct devfreq *df = to_devfreq(dev); >> unsigned long value; >> int ret; >> >> + /* >> + * Protect against theoretical sysfs writes between >> + * device_add and dev_pm_qos_add_request >> + */ >> + if (!dev_pm_qos_request_active(&df->user_min_freq_req)) >> + return -EINVAL; > > The error code -EINVAL is a bit misleading. I guess it's not super > important, especially since this is a very rare case. In case you > re-spin you could consider returning -EAGAIN ('Resource temporarily > unavailable') in this case from min/max_freq_store/show() I agree. -EAGAIN is better than -EINVAL. I'll change it by myself. > > Reviewed-by: Matthias Kaehlcke > Tested-by: Matthias Kaehlcke > > -- Best Regards, Chanwoo Choi Samsung Electronics _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel