linux-kernel - Re: [PATCH v6 12/13] leds: flash: mt6370: Add MediaTek MT6370 flashlight support

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Date:   Mon, 25 Jul 2022 10:55:00 +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 12/13] leds: flash: mt6370: Add MediaTek MT6370
 flashlight support

On Fri, Jul 22, 2022 at 12:25 PM ChiaEn Wu <peterwu.pub@...il.com> wrote:

Forgot to add a couple of things...

...

> +#define MT6370_ITORCH_MIN_UA           25000
> +#define MT6370_ITORCH_STEP_UA          12500
> +#define MT6370_ITORCH_MAX_UA           400000
> +#define MT6370_ITORCH_DOUBLE_MAX_UA    800000
> +#define MT6370_ISTRB_MIN_UA            50000
> +#define MT6370_ISTRB_STEP_UA           12500
> +#define MT6370_ISTRB_MAX_UA            1500000
> +#define MT6370_ISTRB_DOUBLE_MAX_UA     3000000

Perhaps _uA would be better and consistent across your series
regarding current units.

...

> +       /*
> +        * For the flash to turn on/off, need to wait HW ramping up/down time

we need

> +        * 5ms/500us to prevent the unexpected problem.
> +        */
> +       if (!prev && curr)
> +               usleep_range(5000, 6000);
> +       else if (prev && !curr)
> +               udelay(500);

This still remains unanswered, why in the first place we allow
switching, and a busy loop in the other place?

-- 
With Best Regards,
Andy Shevchenko