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[103.229.18.19]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-83965945101sm7346557b3a.13.2026.05.06.23.23.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 May 2026 23:23:22 -0700 (PDT) From: Sibi Sankar To: cristian.marussi@arm.com, sudeep.holla@kernel.org, cw00.choi@samsung.com, kyungmin.park@samsung.com, myungjoo.ham@samsung.com, konradybcio@kernel.org, andersson@kernel.org Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, arm-scmi@vger.kernel.org, linux-tegra@vger.kernel.org, linux-pm@vger.kernel.org, dmitry.baryshkov@oss.qualcomm.com, jonathanh@nvidia.com, thierry.reding@kernel.org, digetx@gmail.com, conor+dt@kernel.org, krzk+dt@kernel.org, robh@kernel.org Subject: [RFC V6 5/8] PM / devfreq: Add a governor for tracking remote device frequencies Date: Thu, 7 May 2026 11:52:34 +0530 Message-Id: <20260507062237.78051-6-sibi.sankar@oss.qualcomm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260507062237.78051-1-sibi.sankar@oss.qualcomm.com> References: <20260507062237.78051-1-sibi.sankar@oss.qualcomm.com> Precedence: bulk X-Mailing-List: linux-tegra@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Proofpoint-ORIG-GUID: euA_YUhvcFmenJU0g9Mbi5RvOBxiH3mk X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTA3MDA2MCBTYWx0ZWRfX2c+E/JJhmI73 sbAD8II9d82VjyTrjLiFHSFpUPxFA2lmEqDrGkhgWFGUVG0uBz8jwBmMJOQ2XSDK2zqjKG0IdqI 02yh2L65r8qgJJFklbeot2Ldr7uaP5KHxBRC0uha4U4fXNdi8MlwX7NMNFt0khN5piAR4tYDFA/ mTOLb9WSGGqQTa2rwQDd95pCLJhvaMRhQW50MOcUj6wqNFNO04g+YC3LKxPYkO/X3w2CCnbWAg9 vRVqF0TGz1tB3e0GaktSLlQGLEh2umwmssWZzk7/Wt2VMCy1F1ik2JywA/vpLRCOnjAMk7sxh3C GItklLwv3hDFI0jCRaWYqmW3cL11sTlXqhhX6Ksr94NycCCCFjqDXAdl0ct0ervgY6T/meCxnFb vOb8wQUFKF9cUb95WvGclEUgMlqIk/3n6kvkpahSLBC8JRhy+/8eK6GUv3bDFtfnuup154xkHKn 60gvm4w7yexHzQBSJNg== X-Proofpoint-GUID: euA_YUhvcFmenJU0g9Mbi5RvOBxiH3mk X-Authority-Analysis: v=2.4 cv=X8Zi7mTe c=1 sm=1 tr=0 ts=69fc2fdc cx=c_pps a=m5Vt/hrsBiPMCU0y4gIsQw==:117 a=Ou0eQOY4+eZoSc0qltEV5Q==:17 a=NGcC8JguVDcA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=yx91gb_oNiZeI1HMLzn7:22 a=EUspDBNiAAAA:8 a=4aD_1Snzd4jiIFQuHjIA:9 a=IoOABgeZipijB_acs4fv:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-06_02,2026-05-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 spamscore=0 adultscore=0 malwarescore=0 lowpriorityscore=0 clxscore=1015 phishscore=0 priorityscore=1501 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605070060 On SoCs, where the governor and the mechanism to control the frequency for devices like caches is hosted on the System Control Processor (SCP), there exists a need track the frequency changes in a reliable way and provide ways to tweaking parameters on the remote governor. To address this introduce the new remote devfreq governor that provides for a way to track the frequency changes on remote devices. It uses the newly introduced target_freq attribute flag and track_remote flag to achieve this. Signed-off-by: Sibi Sankar --- drivers/devfreq/Kconfig | 8 ++++ drivers/devfreq/Makefile | 1 + drivers/devfreq/governor_remote.c | 80 +++++++++++++++++++++++++++++++ include/linux/devfreq.h | 1 + 4 files changed, 90 insertions(+) create mode 100644 drivers/devfreq/governor_remote.c diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig index c999c4a1e567..2caa87554914 100644 --- a/drivers/devfreq/Kconfig +++ b/drivers/devfreq/Kconfig @@ -56,6 +56,14 @@ config DEVFREQ_GOV_POWERSAVE the DEVFREQ framework returns the lowest frequency available at any time. +config DEVFREQ_GOV_REMOTE + tristate "Remote" + help + A simple governor to track the frequency of devices whose + dvfs control lies outside the kernel. This governor acts + as an observer and provides for ways to track frequency and + set/get information related to the remote dvfs device. + config DEVFREQ_GOV_USERSPACE tristate "Userspace" help diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile index 404179d79a9d..cde57c8cda76 100644 --- a/drivers/devfreq/Makefile +++ b/drivers/devfreq/Makefile @@ -4,6 +4,7 @@ obj-$(CONFIG_PM_DEVFREQ_EVENT) += devfreq-event.o obj-$(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND) += governor_simpleondemand.o obj-$(CONFIG_DEVFREQ_GOV_PERFORMANCE) += governor_performance.o obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE) += governor_powersave.o +obj-$(CONFIG_DEVFREQ_GOV_REMOTE) += governor_remote.o obj-$(CONFIG_DEVFREQ_GOV_USERSPACE) += governor_userspace.o obj-$(CONFIG_DEVFREQ_GOV_PASSIVE) += governor_passive.o diff --git a/drivers/devfreq/governor_remote.c b/drivers/devfreq/governor_remote.c new file mode 100644 index 000000000000..6bff3cdaf1e5 --- /dev/null +++ b/drivers/devfreq/governor_remote.c @@ -0,0 +1,80 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) Qualcomm Innovation Center, Inc. All rights reserved. + */ + +#include +#include +#include +#include + +static int devfreq_remote_track_func(struct devfreq *devfreq, unsigned long *freq) +{ + unsigned long cur_freq = 0; + + if (devfreq->profile->get_cur_freq) + devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq); + + *freq = cur_freq; + + return 0; +} + +static int devfreq_remote_track_handler(struct devfreq *devfreq, unsigned int event, void *data) +{ + switch (event) { + case DEVFREQ_GOV_START: + devfreq_monitor_start(devfreq); + break; + + case DEVFREQ_GOV_STOP: + devfreq_monitor_stop(devfreq); + break; + + case DEVFREQ_GOV_UPDATE_INTERVAL: + devfreq_update_interval(devfreq, (unsigned int *)data); + break; + + case DEVFREQ_GOV_SUSPEND: + devfreq_monitor_suspend(devfreq); + break; + + case DEVFREQ_GOV_RESUME: + devfreq_monitor_resume(devfreq); + break; + + default: + break; + } + + return 0; +} + +static struct devfreq_governor devfreq_remote_track = { + .name = DEVFREQ_GOV_REMOTE, + .attrs = DEVFREQ_GOV_ATTR_POLLING_INTERVAL + | DEVFREQ_GOV_ATTR_TIMER, + .flags = DEVFREQ_GOV_FLAG_IMMUTABLE + | DEVFREQ_GOV_FLAG_TRACK_REMOTE, + .get_target_freq = devfreq_remote_track_func, + .event_handler = devfreq_remote_track_handler, +}; + +static int __init devfreq_remote_track_init(void) +{ + return devfreq_add_governor(&devfreq_remote_track); +} +subsys_initcall(devfreq_remote_track_init); + +static void __exit devfreq_remote_track_exit(void) +{ + int ret; + + ret = devfreq_remove_governor(&devfreq_remote_track); + if (ret) + pr_err("%s: failed remove governor %d\n", __func__, ret); +} +module_exit(devfreq_remote_track_exit); + +MODULE_DESCRIPTION("DEVFREQ Remote Tracking governor"); +MODULE_LICENSE("GPL"); diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h index dc1075dc3446..4d50cf230950 100644 --- a/include/linux/devfreq.h +++ b/include/linux/devfreq.h @@ -21,6 +21,7 @@ #define DEVFREQ_GOV_POWERSAVE "powersave" #define DEVFREQ_GOV_USERSPACE "userspace" #define DEVFREQ_GOV_PASSIVE "passive" +#define DEVFREQ_GOV_REMOTE "remote" /* DEVFREQ notifier interface */ #define DEVFREQ_TRANSITION_NOTIFIER (0) -- 2.34.1