linux-kernel - Re: [PATCH v6 2/2] leds: lm3601x: Introduce the lm3601x LED driver

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Date:   Wed, 16 May 2018 16:13:57 -0500
From:   Dan Murphy <dmurphy@...com>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>
CC:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Pavel Machek <pavel@....cz>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>
Subject: Re: [PATCH v6 2/2] leds: lm3601x: Introduce the lm3601x LED driver

Jacek and Andy

On 05/16/2018 04:02 PM, Jacek Anaszewski wrote:
> Hi Andy and Dan,
> 

I will make all the changes then.  I don't want to go through and ack each one.

Thanks for the guidance and the reviews.

It will take a couple days to find all the comments and get this all fixed up.

Dan

> On 05/16/2018 12:24 AM, Andy Shevchenko wrote:
>> On Wed, May 16, 2018 at 1:08 AM, Dan Murphy <dmurphy@...com> wrote:
>>> On 05/15/2018 04:56 PM, Andy Shevchenko wrote:
>>>> On Tue, May 15, 2018 at 6:43 PM, Dan Murphy <dmurphy@...com> wrote:
>>
>>>>> +       depends on LEDS_CLASS && I2C && OF
>>>>
>>>> What is OF specific in this driver?
>>>
>>> as3645a_led_class_setup has a "of" dependency
>>
>> So what? Is it called from this driver or?
>>
>>
>>>>> +static const struct lm3601x_max_timeouts strobe_timeouts[] = {
>>>>> +       { 40000, 0x00 },
>>>>> +       { 80000, 0x01 },
>>>>> +       { 120000, 0x02 },
>>>>> +       { 160000, 0x03 },
>>>>> +       { 200000, 0x04 },
>>>>> +       { 240000, 0x05 },
>>>>> +       { 280000, 0x06 },
>>>>> +       { 320000, 0x07 },
>>>>> +       { 360000, 0x08 },
>>>>> +       { 400000, 0x09 },
>>>>> +       { 600000, 0x0a },
>>>>> +       { 800000, 0x0b },
>>>>> +       { 1000000, 0x0c },
>>>>> +       { 1200000, 0x0d },
>>>>> +       { 1400000, 0x0e },
>>>>> +       { 1600000, 0x0f },
>>>>
>>>> Huh?!
>>>
>>> Please give comments that actually mean something other wise I will opt to ignore them.
>>
>> I did below.
>>
>>>> strobe_timeout = (x + 1) * 40 * MSECS_IN_SEC;
>>>
>>> Not sure what equation you are trying to point out here.  But if you are trying to apply
>>> a timeout step you cannot do this with this part.  As pointed out in the DT doc the timeout
>>> step is not linear.
>>
>> Yeah, I know people are more than often too lazy to think.
>>
>> if (x < 9)
>>   strobe_timeout = (x + 1) * 40 * MSECS_IN_SEC;
>> else
>>   strobe_timeout = (400 + (x - 9) * 200) * MSECS_IN_SEC;
>>
> 
> I like the idea.
> 
>>>>> +               brightness_val = (brightness/2);
>>>>
>>>> Spaces.
>>>
>>> Not sure what this means checkpatch was clean
>>
>> Even besides missed whispaces it has redundant parens.
>>
>> checkpatch is not a silver bullet to get your code clean and nice.
>>
>>>> This is return led_...();
>>>
>>> That is a preference.  It does not have to be that way.
> 
> I missed that. Dan, please follow Andy's advise.
> 
>>
>> What do you mean? We do not appreciate +LOCs for no (or even nagative!) benefit.
>>
>>>>> +               ret = of_property_read_string(led->led_node, "label", &name);
>>>>
>>>> device_property_...();
>>>
>>> It can be if the maintainer is requesting this.
>>
>> Jacek, if you need rationale behind this comment it's here: the driver
>> has nothing DT specific and getting rid of OF centric programming
>> allows to reuse the driver on non-DT platforms w/o touching a source
>> code.
> 
> It has an added value, so yes, let's use it as a standard approach
> from now on.
> 
>>> Is the trend to move to these functions?
>>
>> See above.
>>
>>> Most drivers use the "of" calls.
>>
>> So what?
>>
>>
>>>>> +               if (!ret)
>>>>
>>>> if (ret) sounds more natural. And better just to split
>>>>
>>>>> +                       snprintf(led->led_name, sizeof(led->led_name),
>>>>> +                               "%s:%s", led->led_node->name, name);
>>>>> +               else
>>>>> +                       snprintf(led->led_name, sizeof(led->led_name),
>>>>> +                               "%s:torch", led->led_node->name);
>>>>
>>>> const char *tmp;
>>>>
>>>> ret = device_property_read_...(&tmp);
>>>> if (ret)
>>>>   tmp = ...
>>>> sprintf(...);
> 
> We're no longer taking devicename section of a LED class device name
> from DT, so it will look differently anyway.
> 
>> No comments on this?
>>
>>>>> +       led = devm_kzalloc(&client->dev,
>>>>> +                           sizeof(struct lm3601x_led), GFP_KERNEL);
>>>>
>>>> sizeof(*led) and one line in the result
>>
>> And this?
> 
> Ack.
> 
>>
>>>>> +       { },
>>>>
>>>> Terminators better w/o comma.
>>>
>>> Looking at other drivers adding comma's on the sentinel is accepted.  See the as3645a driver
>>
>> So what?
>>
>> Terminator at compile time even better.
>>
>>>>> +       {},
>>>>
>>>> Ditto.
>>>
>>> See above
>>
>> See above.
>>
> 


-- 
------------------
Dan Murphy