linux-kernel - Re: [PATCH v6 11/13] leds: rgb: mt6370: Add MediaTek MT6370 current sink type LED Indicator support

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Date:   Wed, 27 Jul 2022 12:03:59 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     ChiaEn Wu <peterwu.pub@...il.com>
Cc:     Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>, Pavel Machek <pavel@....cz>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Sebastian Reichel <sre@...nel.org>,
        Chunfeng Yun <chunfeng.yun@...iatek.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        "Krogerus, Heikki" <heikki.krogerus@...ux.intel.com>,
        Helge Deller <deller@....de>,
        ChiaEn Wu <chiaen_wu@...htek.com>,
        Alice Chen <alice_chen@...htek.com>,
        cy_huang <cy_huang@...htek.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        USB <linux-usb@...r.kernel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        "open list:FRAMEBUFFER LAYER" <linux-fbdev@...r.kernel.org>,
        szuni chen <szunichen@...il.com>
Subject: Re: [PATCH v6 11/13] leds: rgb: mt6370: Add MediaTek MT6370 current
 sink type LED Indicator support

On Wed, Jul 27, 2022 at 9:37 AM ChiaEn Wu <peterwu.pub@...il.com> wrote:
> On Tue, Jul 26, 2022 at 8:18 PM Andy Shevchenko
> <andy.shevchenko@...il.com> wrote:
>
> ...
>
> > > Just for saving memory space.
> > > Because these led_classdevs do not be used at the same time.
> > > Or do you think it would be better to rewrite it as follows?
> > > -------------------------------------------------------------------------------------
> > > struct mt6370_led {
> > >        struct led_classdev isink;
> > >        struct led_classdev_mc mc;
> > >        struct mt6370_priv *priv;
> > >        u32 default_state;
> > >        u32 index;
> > > };
> > > -------------------------------------------------------------------------------------
> >
> > You obviously didn't get what I'm talking about...
> > Each union to work properly should have an associated variable that
> > holds the information of which field of the union is in use. Do you
> > have such a variable? If not, how does your code know which one to
> > use? If yes, add a proper comment there.
> >
>
> Ummm... from my understanding,
> if the colors of these four LEDs are set to 'LED_COLOR_ID_RGB' or
> 'LED_COLOR_ID_MULTI' in DT,
> their 'led->index' will be set to 'MT6370_VIRTUAL_MULTICOLOR' in
> 'mt6370_leds_probe()'.
> If so, these led devices will be set as 'struct led_classdev_mc' and
> use related ops functions in 'mt6370_init_led_properties()'.
> Instead, they whose 'led->index' is not 'MT6370_VIRTUAL_MULTICOLOR'
> will be set as 'struct led_classdev'.
> So, maybe the member 'index' of the 'struct mt6370_led' is what you
> describe the information of which field of the union is in use?

>From this description it sounds like it is.

> I will add the proper comment here to describe this thing. I'm so
> sorry for misunderstanding your mean last time.

Yes, please add a compressed version of what you said above to the code.

-- 
With Best Regards,
Andy Shevchenko