linux-kernel - Re: [PATCH v2] dell-laptop: Fix keyboard led max_brightness property for Dell Latitude E6410

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Date:   Wed, 18 Oct 2017 21:14:39 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Matthew Garrett <mjg59@...f.ucam.org>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        "Gabriel M. Elder" <gabriel@...gnowsys.com>,
        Gabriele Mazzotta <gabriele.mzt@...il.com>,
        Mario Limonciello <Mario.Limonciello@...l.com>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] dell-laptop: Fix keyboard led max_brightness property
 for Dell Latitude E6410

On Wednesday 18 October 2017 22:09:41 Andy Shevchenko wrote:
> On Wed, Oct 18, 2017 at 9:06 PM, Pali Rohár <pali.rohar@...il.com> wrote:
> > This machine reports number of keyboard backlight led levels, instead of
> > value of the last led level index. Therefore max_brightness properly needs
> > to be subtracted by 1 to match led max_brightness API.
> >
> > Signed-off-by: Pali Rohár <pali.rohar@...il.com>
> > Reported-by: Gabriel M. Elder <gabriel@...gnowsys.com>
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=196913
> 
> > +       u8 kbd_led_num_of_levels_instead_of_last_index;
> 
> Sorry for last minute review comments.
> 
> First of all, can it be just boolean?

Yes, touchpad_led and needs_kbd_timeouts are booleans too.

> Naming... Yes, too hard as always was, is and will be.
> 
> What about just
> 
> kbd_led_use_levels?

If you code:

  if (quirks->kbd_led_use_levels)
    info->levels--;

Then I think it does not help reader what that quirk represent.

> Also, does it make sense to create a quirks as an unsigned long and
> put there corresponding bits with definitions?

Problem is that part of quirk structure is variable length array
kbd_timeouts. So one unsigned long does not help.

> /* Comment what is this for */
> #define QUIRK_KBD_LED_USE_LEVELS   0
> 
> unsigned long quirks;
> 
> ?
> 
> > +       if (quirks && quirks->kbd_led_num_of_levels_instead_of_last_index && info->levels)
> > +               info->levels--;
> 
> With last suggestion if becomes something like
> 
> if (quirks & BIT(QUIRK_KBD_LED_USE_LEVELS) && info->levels)
> 
> 

-- 
Pali Rohár
pali.rohar@...il.com