linux-kernel - Re: [PATCH v4 13/13] video: backlight: mt6370: Add Mediatek MT6370 support

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Message-ID: <CAHp75VdwEc9AW1w8ejsxkw+sBTF1dumd99QyzTY9BZaXiViRWQ@mail.gmail.com>
Date:   Mon, 4 Jul 2022 23:14:03 +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 v4 13/13] video: backlight: mt6370: Add Mediatek MT6370 support

On Mon, Jul 4, 2022 at 7:43 AM ChiaEn Wu <peterwu.pub@...il.com> wrote:
>
> From: ChiaEn Wu <chiaen_wu@...htek.com>
>
> Add Mediatek MT6370 Backlight support.

...

> +         This driver can also be built as a module. If so the module

If so,

> +         will be called "mt6370-backlight.ko".

No ".ko" part.

...

> +#include <linux/gpio/driver.h>

Can you elaborate on this?

> +#include <linux/kernel.h>
> +#include <linux/log2.h>
> +#include <linux/minmax.h>
> +#include <linux/module.h>

> +#include <linux/of.h>

Can you elaborate on this?

> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>

Missed mod_devicetable.h.

...

> +               brightness_val[0] = (brightness - 1) & MT6370_BL_DIM2_MASK;
> +               brightness_val[1] = (brightness - 1)
> +                                   >> fls(MT6370_BL_DIM2_MASK);

Bad indentation. One line?

...

> +       if (priv->enable_gpio)

Dup check.

> +               gpiod_set_value(priv->enable_gpio, brightness ? 1 : 0);

...

> +       brightness = brightness_val[1] << fls(MT6370_BL_DIM2_MASK);
> +       brightness += (brightness_val[0] & MT6370_BL_DIM2_MASK);

Too many parentheses.

...

> +               /*
> +                * prop_val =  1      -->  1 steps --> 0x00
> +                * prop_val =  2 ~  4 -->  4 steps --> 0x01
> +                * prop_val =  5 ~ 16 --> 16 steps --> 0x10
> +                * prop_val = 17 ~ 64 --> 64 steps --> 0x11
> +                */
> +               prop_val = (ilog2(roundup_pow_of_two(prop_val)) + 1) >> 1;

Isn't something closer to get_order() or fls()?

...

> +       props->max_brightness = min_t(u32, brightness,
> +                                     MT6370_BL_MAX_BRIGHTNESS);

One line?

...

> +       val = 0;

Do you need this here?

> +       prop_val = 0;

Useless.

> +       ret = device_property_read_u8(dev, "mediatek,bled-channel-use",
> +                                     &prop_val);
> +       if (ret) {
> +               dev_err(dev, "mediatek,bled-channel-use DT property missing\n");
> +               return ret;
> +       }
> +
> +       if (!prop_val || prop_val > MT6370_BL_MAX_CH) {
> +               dev_err(dev,
> +                       "No channel specified or over than upper bound (%d)\n",
> +                       prop_val);
> +               return -EINVAL;
> +       }

...

> +static int mt6370_bl_probe(struct platform_device *pdev)
> +{
> +       struct mt6370_priv *priv;
> +       struct backlight_properties props = {
> +               .type = BACKLIGHT_RAW,
> +               .scale = BACKLIGHT_SCALE_LINEAR,
> +       };
> +       int ret;

  struct device *dev = &pdev->dev;

will save you a few LoCs.

-- 
With Best Regards,
Andy Shevchenko