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

[Jacek Anaszewski]

Hi Andy and Dan,

On 05/16/2018 12:24 AM, Andy Shevchenko wrote:
> On Wed, May 16, 2018 at 1:08 AM, Dan Murphy <dmurphy@xxxxxx> wrote:
> > On 05/15/2018 04:56 PM, Andy Shevchenko wrote:
> > > On Tue, May 15, 2018 at 6:43 PM, Dan Murphy <dmurphy@xxxxxx> 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.

--
Best regards,
Jacek Anaszewski