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Wed, 29 Apr 2026 15:28:05 -0700 (PDT) Message-ID: <7a500e85-d20d-47f8-b4ce-7015052193c7@gmail.com> Date: Thu, 30 Apr 2026 07:28:02 +0900 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/4] PM / devfreq: Fix governor_store() failing when device has no current governor Content-Language: ko To: Yaxiong Tian , myungjoo.ham@samsung.com, kyungmin.park@samsung.com, cw00.choi@samsung.com, zhanjie9@hisilicon.com, nm@ti.com Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260401032838.66168-1-tianyaxiong@kylinos.cn> <20260401033119.67821-1-tianyaxiong@kylinos.cn> From: Choi Chanwoo In-Reply-To: <20260401033119.67821-1-tianyaxiong@kylinos.cn> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 2026-04-01 PM 12:31에 Yaxiong Tian 이(가) 쓴 글: > Since devfreq_remove_governor() may clear the device's current governor > in certain situations, while governors actually exist independently > of the device, directly returning EINVAL in this case is inaccurate. > > To fix this issue, remove this check and add relevant logic for when > df->governor is NULL. > > Fixes: 483d557ee9a3 ("PM / devfreq: Clean up the devfreq instance name in sysfs attr") > Signed-off-by: Yaxiong Tian > --- > drivers/devfreq/devfreq.c | 17 ++++++++++++++--- > 1 file changed, 14 insertions(+), 3 deletions(-) > > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c > index 2977b07be939..975f82d7a9d1 100644 > --- a/drivers/devfreq/devfreq.c > +++ b/drivers/devfreq/devfreq.c > @@ -1390,9 +1390,6 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, > char str_governor[DEVFREQ_NAME_LEN + 1]; > const struct devfreq_governor *governor, *prev_governor; > > - if (!df->governor) > - return -EINVAL; > - > ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor); > if (ret != 1) > return -EINVAL; > @@ -1403,6 +1400,20 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, > ret = PTR_ERR(governor); > goto out; > } > + > + if (!df->governor) { > + df->governor = governor; > + ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL); > + if (ret) { > + dev_warn(dev, "%s: Governor %s not started(%d)\n", > + __func__, df->governor->name, ret); > + df->governor = NULL; > + } else { > + ret = sysfs_update_group(&df->dev.kobj, &gov_attr_group); > + } > + goto out; > + } > + > if (df->governor == governor) { > ret = 0; > goto out; Hi, I think that the following patch is able to support on your case. Could you please check it? diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c index e5d3f9cf94dc..f08fc6966eae 100644 --- a/drivers/devfreq/devfreq.c +++ b/drivers/devfreq/devfreq.c @@ -1390,9 +1390,6 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, char str_governor[DEVFREQ_NAME_LEN + 1]; const struct devfreq_governor *governor, *prev_governor; - if (!df->governor) - return -EINVAL; - ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor); if (ret != 1) return -EINVAL; @@ -1403,6 +1400,9 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, ret = PTR_ERR(governor); goto out; } + if (!df->governor) + goto start_new_governor; + if (df->governor == governor) { ret = 0; goto out; @@ -1423,6 +1423,7 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, goto out; } +start_new_governor: /* * Start the new governor and create the specific sysfs files * which depend on the new governor. @@ -1436,6 +1437,9 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr, /* Restore previous governor */ df->governor = prev_governor; + if (!df->governor) + goto out; + Thanks, Chanwoo Choi