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[79.139.233.37]) by smtp.googlemail.com with ESMTPSA id o10sm1479361lfn.20.2020.01.08.06.14.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Jan 2020 06:14:20 -0800 (PST) Subject: Re: [PATCH 1/2] PM / devfreq: Add debugfs support with devfreq_summary file To: Chanwoo Choi , Bjorn Andersson Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, leonard.crestez@nxp.com, lukasz.luba@arm.com, a.swigon@samsung.com, m.szyprowski@samsung.com, enric.balletbo@collabora.com, hl@rock-chips.com, jcrouse@codeaurora.org, chanwoo@kernel.org, myungjoo.ham@samsung.com, kyungmin.park@samsung.com References: <20200107090519.3231-1-cw00.choi@samsung.com> <20200107090519.3231-2-cw00.choi@samsung.com> <20200107211558.GA738324@yoga> <19fd2201-2a7d-46df-09cf-e39f6668b488@samsung.com> From: Dmitry Osipenko Message-ID: Date: Wed, 8 Jan 2020 17:14:19 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <19fd2201-2a7d-46df-09cf-e39f6668b488@samsung.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 08.01.2020 10:56, Chanwoo Choi пишет: > On 1/8/20 6:15 AM, Bjorn Andersson wrote: >> On Tue 07 Jan 01:05 PST 2020, Chanwoo Choi wrote: >> >>> Add debugfs interface to provide debugging information of devfreq device. >>> It contains 'devfreq_summary' entry to show the summary of registered >>> devfreq devices as following and the additional debugfs file will be added. >>> - /sys/kernel/debug/devfreq/devfreq_summary >>> >>> [Detailed description of each field of 'devfreq_summary' debugfs file] >>> - dev_name : Device name of h/w. >>> - dev : Device name made by devfreq core. >>> - parent_dev : If devfreq device uses the passive governor, >>> show parent devfreq device name. >>> - governor : Devfreq governor. >>> - polling_ms : If devfreq device uses the simple_ondemand governor, >>> polling_ms is necessary for the period. (unit: millisecond) >>> - cur_freq_hz : Current Frequency (unit: hz) >>> - old_freq_hz : Frequency before changing. (unit: hz) >>> - new_freq_hz : Frequency after changed. (unit: hz) >>> >>> [For example on Exynos5422-based Odroid-XU3 board] >>> - In order to show the multiple governors on devfreq_summay result, >>> change the governor of devfreq0 from simple_ondemand to userspace. >>> >>> $ cat /sys/kernel/debug/devfreq/devfreq_summary >>> dev_name dev parent_dev governor polling_ms cur_freq_hz min_freq_hz max_freq_hz >>> ------------------------------ ---------- ---------- --------------- ---------- ------------ ------------ ------------ >>> 10c20000.memory-controller devfreq0 userspace 0 206000000 165000000 825000000 >>> soc:bus_wcore devfreq1 simple_ondemand 50 532000000 88700000 532000000 >>> soc:bus_noc devfreq2 devfreq1 passive 0 111000000 66600000 111000000 >>> soc:bus_fsys_apb devfreq3 devfreq1 passive 0 222000000 111000000 222000000 >>> soc:bus_fsys devfreq4 devfreq1 passive 0 200000000 75000000 200000000 >>> soc:bus_fsys2 devfreq5 devfreq1 passive 0 200000000 75000000 200000000 >>> soc:bus_mfc devfreq6 devfreq1 passive 0 333000000 83250000 333000000 >>> soc:bus_gen devfreq7 devfreq1 passive 0 266000000 88700000 266000000 >>> soc:bus_peri devfreq8 devfreq1 passive 0 66600000 66600000 66600000 >>> soc:bus_g2d devfreq9 devfreq1 passive 0 0 83250000 333000000 >>> soc:bus_g2d_acp devfreq10 devfreq1 passive 0 0 66500000 266000000 >>> soc:bus_jpeg devfreq11 devfreq1 passive 0 0 75000000 300000000 >>> soc:bus_jpeg_apb devfreq12 devfreq1 passive 0 0 83250000 166500000 >>> soc:bus_disp1_fimd devfreq13 devfreq1 passive 0 0 120000000 200000000 >>> soc:bus_disp1 devfreq14 devfreq1 passive 0 0 120000000 300000000 >>> soc:bus_gscl_scaler devfreq15 devfreq1 passive 0 0 150000000 300000000 >>> soc:bus_mscl devfreq16 devfreq1 passive 0 0 84000000 666000000 >> >> This looks quite useful. >> >>> >>> Reported-by: kbuild test robot >> >> May I ask how the build test robot came up with this idea? > > I'm missing the detailed what are the reported by kbuild test robot. > It reported the possible build error. I'll add the following description > on next version: > [lkp: Reported the build error] > >> >>> Signed-off-by: Chanwoo Choi >>> --- >>> drivers/devfreq/devfreq.c | 80 +++++++++++++++++++++++++++++++++++++++ >>> 1 file changed, 80 insertions(+) >>> >>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c >> [..] >>> +/** >>> + * devfreq_summary_show() - Show the summary of the registered devfreq devices >>> + * via 'devfreq_summary' debugfs file. >> >> Please make this proper kerneldoc, i.e: >> >> * func() - short description >> * @s: >> * @data: >> * >> * Long description >> * >> * Return: foo on bar > > OK. > >> >> [..] >>> @@ -1733,6 +1803,16 @@ static int __init devfreq_init(void) >>> } >>> devfreq_class->dev_groups = devfreq_groups; >>> >>> + devfreq_debugfs = debugfs_create_dir("devfreq", NULL); >>> + if (PTR_ERR(devfreq_debugfs) != -ENODEV && IS_ERR(devfreq_debugfs)) { >> >> Don't PTR_ERR() before IS_ERR(). > > Before checking IS_ERR(), have to check the PTR_ERR(devfreq_debugfs) > is -ENODEV or not because debugfs_create_dir return the '-ENODEV' > if DEBUG_FS is disabled. If return the -ENODEV, it is not error. You could write it this way: devfreq_debugfs = debugfs_create_dir("devfreq", NULL); err = PTR_ERR_OR_ZERO(devfreq_debugfs); if (err && err != -ENODEV) { ...