Date:   Thu, 6 Jun 2019 14:11:00 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Ezequiel Garcia <ezequiel@...labora.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Guenter Roeck <groeck@...gle.com>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Gwendal Grignou <gwendal@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        Benson Leung <bleung@...omium.org>,
        Lee Jones <lee.jones@...aro.org>, kernel@...labora.com,
        Dmitry Torokhov <dtor@...omium.org>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        linux-doc@...r.kernel.org, Enno Luebbers <enno.luebbers@...el.com>,
        Guido Kiener <guido@...ner-muenchen.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kishon Vijay Abraham I <kishon@...com>,
        Jonathan Corbet <corbet@....net>, Wu Hao <hao.wu@...el.com>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Tycho Andersen <tycho@...ho.ws>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Jilayne Lovejoy <opensource@...ayne.com>
Subject: Re: [PATCH 03/10] mfd / platform: cros_ec: Miscellaneous character
 device to talk with the EC

On 6/6/19 8:12 AM, Ezequiel Garcia wrote:
> On Thu, 2019-06-06 at 16:51 +0200, Greg Kroah-Hartman wrote:
>> On Thu, Jun 06, 2019 at 11:01:17AM -0300, Ezequiel Garcia wrote:
>>> On Tue, 2019-06-04 at 20:59 +0200, Greg Kroah-Hartman wrote:
>>>> On Tue, Jun 04, 2019 at 11:39:21AM -0700, Guenter Roeck wrote:
>>>>> On Tue, Jun 4, 2019 at 11:35 AM Greg Kroah-Hartman
>>>>> <gregkh@...uxfoundation.org> wrote:
>>>>>> On Tue, Jun 04, 2019 at 01:58:38PM -0300, Ezequiel Garcia wrote:
>>>>>>> Hey Greg,
>>>>>>>
>>>>>>>>> + dev_info(&pdev->dev, "Created misc device /dev/%s\n",
>>>>>>>>> +          data->misc.name);
>>>>>>>>
>>>>>>>> No need to be noisy, if all goes well, your code should be quiet.
>>>>>>>>
>>>>>>>
>>>>>>> I sometimes wonder about this being noise or not, so I will slightly
>>>>>>> hijack this thread for this discussion.
>>>>>>>
>>>>>>>> From a kernel developer point-of-view, or even from a platform
>>>>>>> developer or user with a debugging hat point-of-view, having
>>>>>>> a "device created" or "device registered" message is often very useful.
>>>>>>
>>>>>> For you, yes.  For someone with 30000 devices attached to their system,
>>>>>> it is not, and causes booting to take longer than it should be.
>>>>>>
>>>>>>> In fact, I wish people would do this more often, so I don't have to
>>>>>>> deal with dynamic debug, or hack my way:
>>>>>>>
>>>>>>> diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
>>>>>>> index 4589631798c9..473549b26bb2 100644
>>>>>>> --- a/drivers/media/i2c/ov5647.c
>>>>>>> +++ b/drivers/media/i2c/ov5647.c
>>>>>>> @@ -603,7 +603,7 @@ static int ov5647_probe(struct i2c_client *client,
>>>>>>>         if (ret < 0)
>>>>>>>                 goto error;
>>>>>>>
>>>>>>> -       dev_dbg(dev, "OmniVision OV5647 camera driver probed\n");
>>>>>>> +       dev_info(dev, "OmniVision OV5647 camera driver probed\n");
>>>>>>>         return 0;
>>>>>>>  error:
>>>>>>>         media_entity_cleanup(&sd->entity);
>>>>>>>
>>>>>>> In some subsystems, it's even a behavior I'm more or less relying on:
>>>>>>>
>>>>>>> $ git grep v4l2_info.*registered drivers/media/ | wc -l
>>>>>>> 26
>>>>>>>
>>>>>>> And on the downsides, I can't find much. It's just one little line,
>>>>>>> that is not even noticed unless you have logging turned on.
>>>>>>
>>>>>> Its better to be quiet, which is why the "default driver registration"
>>>>>> macros do not have any printk messages in them.  When converting drivers
>>>>>> over to it, we made the boot process much more sane, don't try to go and
>>>>>> add messages for no good reason back in please.
>>>>>>
>>>>>> dynamic debugging can be enabled on a module and line-by-line basis,
>>>>>> even from the boot command line.  So if you need debugging, you can
>>>>>> always ask someone to just reboot or unload/load the module and get the
>>>>>> message that way.
>>>>>>
>>>>>
>>>>> Can we by any chance make this an official policy ? I am kind of tired
>>>>> having to argue about this over and over again.
>>>>
>>>> Sure, but how does anyone make any "official policy" in the kernel?  :)
>>>>
>>>> I could just go through and delete all "look ma, a new driver/device!"
>>>> messages, but that might be annoying...
>>>>
>>>
>>> Well, I really need to task.
>>
>> ???
>>
> 
> Oops, typo: s/task/ask :-)
> 
>>> If it's not an official policy (and won't be anytime soon?),
>>
>> The ":)" there was that we really have very few "official" policies,
>> only things that we all strongly encourage to happen.  And get grumpy if
>> we see them in code reviews.  Like I did here.
>>
> 
> Well, not everyone gets grumpy. As I pointed out, we use this "registered"
> messages (messages or noise, seems this lie in the eye of the beholder),
> consistently across entire subsystems.

:(

>>> then what's preventing Enric from pushing this print on this driver,
>>> given he is the one maintaining the code?
>>
>> Given that he wants people to review his code, why would you tell him to
>> ignore what people are trying to tell him?
>>
> 
> I'm not suggesting to ignore anyone, rather to consider all voices
> involved in each review comment.
> 
>> Again, don't be noisy, it's not hard, and is how things have been
>> trending for many years now.

Ack that.


-- 
~Randy

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