Re: [PATCH v2] PM / devfreq: Add debugfs support with devfreq_summary file

[Chanwoo Choi]

On 1/14/20 3:18 AM, Leonard Crestez wrote:
> On 13.01.2020 06:56, 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]
>> $ 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              simple_ondemand          0    165000000    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    333000000     83250000    333000000
>> soc:bus_g2d_acp                devfreq10  devfreq1   passive                  0    266000000     66500000    266000000
>> soc:bus_jpeg                   devfreq11  devfreq1   passive                  0    300000000     75000000    300000000
>> soc:bus_jpeg_apb               devfreq12  devfreq1   passive                  0    166500000     83250000    166500000
>> soc:bus_disp1_fimd             devfreq13  devfreq1   passive                  0    200000000    120000000    200000000
>> soc:bus_disp1                  devfreq14  devfreq1   passive                  0    300000000    120000000    300000000
>> soc:bus_gscl_scaler            devfreq15  devfreq1   passive                  0    300000000    150000000    300000000
>> soc:bus_mscl                   devfreq16  devfreq1   passive                  0    666000000     84000000    666000000
>>
>> [lkp: Reported the build error]
>> Reported-by: kbuild test robot <lkp@xxxxxxxxx>
>> Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
>> ---
>> Changes from v1:
>> - Drop the patch about 'devfreq_transitions' debugfs file
>> - Modify from 'hz' to 'Hz'
>> - Edit the indentation of 'devfreq_summary' when show summary
>> - Exchange sequence between PTR_ERR and IS_ERR when debugfs_create_dir
>>
>>   drivers/devfreq/devfreq.c | 84 +++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 84 insertions(+)
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index 89260b17598f..c2ebed42704b 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -10,6 +10,7 @@
>>   #include <linux/kernel.h>
>>   #include <linux/kmod.h>
>>   #include <linux/sched.h>
>> +#include <linux/debugfs.h>
>>   #include <linux/errno.h>
>>   #include <linux/err.h>
>>   #include <linux/init.h>
>> @@ -33,6 +34,7 @@
>>   #define HZ_PER_KHZ	1000
>>   
>>   static struct class *devfreq_class;
>> +static struct dentry *devfreq_debugfs;
>>   
>>   /*
>>    * devfreq core provides delayed work based load monitoring helper
>> @@ -1643,6 +1645,79 @@ static struct attribute *devfreq_attrs[] = {
>>   };
>>   ATTRIBUTE_GROUPS(devfreq);
>>   
>> +/**
>> + * devfreq_summary_show() - Show the summary of the devfreq devices
>> + * @s:		seq_file instance to show the summary of devfreq devices
>> + * @data:	not used
>> + *
>> + * Show the summary of the devfreq devices via 'devfreq_summary' debugfs file.
>> + * It helps that user can know the detailed information of the devfreq devices.
>> + *
>> + * Return 0 always because it shows the information without any data change.
>> + */
>> +static int devfreq_summary_show(struct seq_file *s, void *data)
>> +{
>> +	struct devfreq *devfreq;
>> +	struct devfreq *p_devfreq = NULL;
>> +	unsigned long cur_freq, min_freq, max_freq;
>> +	unsigned int polling_ms;
>> +
>> +	seq_printf(s, "%-30s %-10s %-10s %-15s %10s %12s %12s %12s\n",
>> +			"dev_name",
>> +			"dev",
>> +			"parent_dev",
>> +			"governor",
>> +			"polling_ms",
>> +			"cur_freq_Hz",
>> +			"min_freq_Hz",
>> +			"max_freq_Hz");
>> +	seq_printf(s, "%30s %10s %10s %15s %10s %12s %12s %12s\n",
>> +			"------------------------------",
>> +			"----------",
>> +			"----------",
>> +			"---------------",
>> +			"----------",
>> +			"------------",
>> +			"------------",
>> +			"------------");
>> +
>> +	mutex_lock(&devfreq_list_lock);
>> +
>> +	list_for_each_entry_reverse(devfreq, &devfreq_list, node) {
>> +		if (!strncmp(devfreq->governor_name, DEVFREQ_GOV_PASSIVE,
>> +							DEVFREQ_NAME_LEN)) {
>> +			struct devfreq_passive_data *data = devfreq->data;
>> +
>> +			if (data)
>> +				p_devfreq = data->parent;
>> +		} else {
>> +			p_devfreq = NULL;
>> +		}
>> +
>> +		mutex_lock(&devfreq->lock);
>> +		cur_freq = devfreq->previous_freq,
>> +		get_freq_range(devfreq, &min_freq, &max_freq);
>> +		polling_ms = devfreq->profile->polling_ms,
>> +		mutex_unlock(&devfreq->lock);
>> +
>> +		seq_printf(s,
>> +			"%-30s %-10s %-10s %-15s %10d %12ld %12ld %12ld\n",
>> +			dev_name(devfreq->dev.parent),
>> +			dev_name(&devfreq->dev),
>> +			p_devfreq ? dev_name(&p_devfreq->dev) : "",
> 
> Can you prints some sort of "null" here instead of just skipping the field?
> 
> This would ensure output is always a whitespace-separated table that can 
> be easily processed with tools like "awk".

OK.
I had considered what is better to show 'null' or not.
If there is requirement, print 'null'.

> 
>> +			devfreq->governor_name,
>> +			polling_ms,
>> +			cur_freq,
>> +			min_freq,
>> +			max_freq);
>> +	}
>> +
>> +	mutex_unlock(&devfreq_list_lock);
>> +
>> +	return 0;
>> +}
>> +DEFINE_SHOW_ATTRIBUTE(devfreq_summary);
>> +
>>   static int __init devfreq_init(void)
>>   {
>>   	devfreq_class = class_create(THIS_MODULE, "devfreq");
>> @@ -1659,6 +1734,15 @@ static int __init devfreq_init(void)
>>   	}
>>   	devfreq_class->dev_groups = devfreq_groups;
>>   
>> +	devfreq_debugfs = debugfs_create_dir("devfreq", NULL);
>> +	if (IS_ERR(devfreq_debugfs) && PTR_ERR(devfreq_debugfs) != -ENODEV) {
>> +		pr_warn("%s: couldn't create debugfs dir\n", __FILE__); > +	} else {
>> +		debugfs_create_file("devfreq_summary", 0444,
>> +				devfreq_debugfs, NULL,
>> +				&devfreq_summary_fops);
>> +	}
>> +
>>   	return 0;
>>   }
>>   subsys_initcall(devfreq_init);
>>
> 
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics