linux-kernel - Re: [PATCH v3 2/2] leds: lgm: Add LED controller driver for LGM SoC

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Date:   Tue, 2 Mar 2021 11:36:27 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Amireddy Mallikarjuna reddy <mallikarjunax.reddy@...ux.intel.com>
Cc:     linux-leds <linux-leds@...r.kernel.org>,
        Pavel Machek <pavel@....cz>, Dan Murphy <dmurphy@...com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Rob Herring <robh+dt@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        cheol.yong.kim@...el.com, qi-ming.wu@...el.com,
        malliamireddy009@...il.com, yixin.zhu@...el.com
Subject: Re: [PATCH v3 2/2] leds: lgm: Add LED controller driver for LGM SoC

Hi Amireddy,

On Thu, Dec 10, 2020 at 10:20 AM Amireddy Mallikarjuna reddy
<mallikarjunax.reddy@...ux.intel.com> wrote:
> Parallel to serial conversion, which is also called SSO controller,
> can drive external shift register for LED outputs, reset or
> general purpose outputs.
>
> This driver enables LED support for Serial Shift Output Controller (SSO).
>
> Signed-off-by: Amireddy Mallikarjuna reddy <mallikarjunax.reddy@...ux.intel.com>

Thanks for your patch, which is now commit c3987cd2bca34ddf ("leds: lgm:
Add LED controller driver for LGM SoC") in v5.12-rc1.

> --- /dev/null
> +++ b/drivers/leds/blink/Kconfig
> @@ -0,0 +1,20 @@
> +menuconfig LEDS_BLINK
> +       bool "LED Blink support"
> +       depends on LEDS_CLASS
> +       help
> +         This option enables blink support for the leds class.
> +         If unsure, say Y.

What is the purpose of the LEDS_BLINK config symbol?
Blink support for the leds class is always available, regardless of the
value of this symbol, and controlled for individual drivers by filling
in the led_classdev.blink_set() callback.

> +
> +if LEDS_BLINK
> +
> +config LEDS_BLINK_LGM
> +       tristate "LED support for Intel LGM SoC series"
> +       depends on LEDS_CLASS
> +       depends on MFD_SYSCON
> +       depends on OF
> +       help
> +         Parallel to serial conversion, which is also called SSO controller,
> +         can drive external shift register for LED outputs.
> +         This enables LED support for Serial Shift Output controller(SSO).

What's so special about this driver that it needs a new "blink" subdir?
Isn't it an ordinary LED driver?
Looking at the code filling in the .blink_set() callback, the hardware
blink feature seems to be even optional?

> +
> +endif # LEDS_BLINK

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds