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Wed, 31 Jul 2019 09:29:57 +0900 (KST) Received: from [10.113.221.102] (unknown [10.113.221.102]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20190731002956epsmtip16320b414752961c44fae2aa4dd52b64c~2Vni1iQYZ2271322713epsmtip1G; Wed, 31 Jul 2019 00:29:56 +0000 (GMT) Subject: Re: [PATCH] PM / devfreq: Drop the name check to request module in try_then_request_governor() To: Yue Hu , myungjoo.ham@samsung.com, kyungmin.park@samsung.com Cc: linux-pm@vger.kernel.org, huyue2@yulong.com From: Chanwoo Choi Organization: Samsung Electronics Message-ID: <8e5efa9c-96c4-0c2c-b92a-d72ee598838c@samsung.com> Date: Wed, 31 Jul 2019 09:33:06 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190730100819.8056-1-zbestahu@gmail.com> Content-Language: en-US Content-Transfer-Encoding: 8bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprKJsWRmVeSWpSXmKPExsWy7bCmni7rQ4dYg8cvJSz2zL7LbHG26Q27 xefeI4wWtxtXsFnMPcXlwOqxc9Zddo++LasYPT5vkvPYumYxcwBLVLZNRmpiSmqRQmpecn5K Zl66rZJ3cLxzvKmZgaGuoaWFuZJCXmJuqq2Si0+ArltmDtBaJYWyxJxSoFBAYnGxkr6dTVF+ aUmqQkZ+cYmtUmpBSk6BZYFecWJucWleul5yfq6VoYGBkSlQYUJ2RvPSa8wFJ4Ur3rw8y97A 2CbQxcjJISFgInHw+WXWLkYuDiGBHYwSz/9cYgVJCAl8YpTYvDMfIvGNUeJNbz8TTMeylm1s EIm9jBK7/lxggnDeM0q0rLoC1i4skCnx9MZiFhBbRCBM4urjF4wgNrOAvsTNJe+ZQWw2AS2J /S9usIHY/AKKEld/PAar4RWwk7h5tBlsDouAqsT77UvAbFGBCIlPDw6zQtQISpyc+QRsPqeA ucTlLROh5otL3HoynwnClpdo3jqbGeQ4CYHrbBKXl3SzQrzgInH+30xmCFtY4tXxLewQtpTE y/42KLtaYuXJI2wQzR2MElv2X4BqNpbYv3Qy0AYOoA2aEut36UOEFSV2/p4LdQSfxLuvPawg JRICvBIdbUIQJcoSlx/chYaipMTi9k62CYxKs5C8MwvJC7OQvDALYdkCRpZVjGKpBcW56anF hgVGyLG9iRGcJLXMdjAuOudziFGAg1GJh/dErEOsEGtiWXFl7iFGCQ5mJRHexeL2sUK8KYmV ValF+fFFpTmpxYcYTYGhPZFZSjQ5H5jA80riDU2NjI2NLUwMzUwNDZXEeRf+sIgVEkhPLEnN Tk0tSC2C6WPi4JRqYGTN7DNZ27FmUZ+c4v3PijwlH369ZPesETud/CbvVI2Hxe0U5kLHo8o3 dDX79D1npqjsPeV+sTk96MqPp+c1NGUD7scF/vplXbT0A//P9e92dkfK7mZQ/sl9VS1YR1kl zPY+4589shHWnOX/7k4TETraZqVxpCykrU7t265jn6fJHTlz1GnlZyWW4oxEQy3mouJEAGsr 37+oAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmpgkeLIzCtJLcpLzFFi42LZdlhJTpf1oUOswca/rBZ7Zt9ltjjb9Ibd 4nPvEUaL240r2CzmnuJyYPXYOesuu0ffllWMHp83yXlsXbOYOYAlissmJTUnsyy1SN8ugSuj eek15oKTwhVvXp5lb2BsE+hi5OSQEDCRWNayja2LkYtDSGA3o8TpE9fZIBKSEtMuHmXuYuQA soUlDh8uhqh5yyixdedWVpAaYYFMiac3FrOA2CICYRL9vZOZQGxmAX2Jm0veM0M0dAE1TNzB CJJgE9CS2P/iBtgCfgFFias/HoPFeQXsJG4ebQYbyiKgKvF++xIwW1QgQuLwjllQNYISJ2c+ AVvGKWAucXnLREaIZeoSf+ZdYoawxSVuPZkPdYS8RPPW2cwTGIVnIWmfhaRlFpKWWUhaFjCy rGKUTC0ozk3PLTYsMMxLLdcrTswtLs1L10vOz93ECI4XLc0djJeXxB9iFOBgVOLhPRHrECvE mlhWXJl7iFGCg1lJhHexuH2sEG9KYmVValF+fFFpTmrxIUZpDhYlcd6neccihQTSE0tSs1NT C1KLYLJMHJxSDYyqr964b3F3+3C2UiW7Xi/G8D2f/oRTe14cy404+dNRaQaH2LfwVNOS1opF Em4vf3nnL7rwOJBRdedZA4FtQdNOGheebxZdyK9iuVH/doZ/usWUBUnnHq3kMc08fXHK45+T 73ZJVWUIb1U18Yp57PK1ZLuMpfu/252z5hZ/UikV+dP8hPtvN4sSS3FGoqEWc1FxIgA4mQB0 kwIAAA== X-CMS-MailID: 20190731002957epcas1p4ed4e79fa6d81dedc8aef3e17e7459668 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: SVC_REQ_APPROVE CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20190730100844epcas4p14dfa39fff2636e89c94033f154240db0 References: <20190730100819.8056-1-zbestahu@gmail.com> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 19. 7. 30. 오후 7:08, Yue Hu wrote: > From: Yue Hu > > No need to check specific governor name of `simple_ondemand` to request > module, let's change the name string to `simpleondemand` to keep the > consistency on loading module if needed. NACK. hmm.... It is impossible to change the devfreq governor name because there are many reason. The devfreq governor could be changed through the sysfs interface on runtime. For a long time, many users or platforms change the devfreq governor with the defined governor name through sysfs. If it is just changed, it breaks ABI interface and cannot support the compatibility. It is very critical problem. Please drop it. Maybe, you didn't check the usage of devfreq device driver in the mainline kernel. Almost devfreq device using simple_ondemand governor have to add the governor name with devfreq_add_device(). If changed the governor name, it cause the fault of device driver using the devfreq framework with simple_ondemand. > > Signed-off-by: Yue Hu > --- > drivers/devfreq/devfreq.c | 6 +----- > include/linux/devfreq.h | 2 +- > 2 files changed, 2 insertions(+), 6 deletions(-) > > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c > index 784c08e..baff682 100644 > --- a/drivers/devfreq/devfreq.c > +++ b/drivers/devfreq/devfreq.c > @@ -246,11 +246,7 @@ static struct devfreq_governor *try_then_request_governor(const char *name) > if (IS_ERR(governor)) { > mutex_unlock(&devfreq_list_lock); > > - if (!strncmp(name, DEVFREQ_GOV_SIMPLE_ONDEMAND, > - DEVFREQ_NAME_LEN)) > - err = request_module("governor_%s", "simpleondemand"); > - else > - err = request_module("governor_%s", name); > + err = request_module("governor_%s", name); > /* Restore previous state before return */ > mutex_lock(&devfreq_list_lock); > if (err) > diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h > index 2bae9ed..41e8792 100644 > --- a/include/linux/devfreq.h > +++ b/include/linux/devfreq.h > @@ -17,7 +17,7 @@ > #define DEVFREQ_NAME_LEN 16 > > /* DEVFREQ governor name */ > -#define DEVFREQ_GOV_SIMPLE_ONDEMAND "simple_ondemand" > +#define DEVFREQ_GOV_SIMPLE_ONDEMAND "simpleondemand" > #define DEVFREQ_GOV_PERFORMANCE "performance" > #define DEVFREQ_GOV_POWERSAVE "powersave" > #define DEVFREQ_GOV_USERSPACE "userspace" > -- Best Regards, Chanwoo Choi Samsung Electronics