Re: [PATCH v2 15/15] video: backlight: mt6370: Add Mediatek MT6370 support

[ChiaEn Wu <peterwu.pub@gmail.com>]

Hi Daniel,

Thanks for your helpful feedback!

Daniel Thompson <daniel.thompson@linaro.org> 於 2022年6月14日 週二 凌晨1:08寫道：
>
> On Mon, Jun 13, 2022 at 07:11:46PM +0800, ChiaEn Wu wrote:
> > +static int mt6370_init_backlight_properties(struct mt6370_priv *priv,
> > +                                         struct backlight_properties *props)
>
> Most of the changes in this version looks good... but it looks the new
> code in this function has a number of problems. See below...
>
>
> > +{
> > +     struct device *dev = priv->dev;
> > +     u8 prop_val;
> > +     u32 brightness;
> > +     unsigned int mask, val;
> > +     int ret;
> > +
> > +     /* Vendor optional properties
> > +      * if property not exist, keep value in default.
> > +      */
>
> That's not the right strategy for booleans. Not existing means false
> (e.g. flags should actively be unset).
>

I am so sorry for making these mistakes...
I will try to refine them in the right strategy in the next patch!

>
> > +     if (device_property_read_bool(dev, "mediatek,bled-pwm-enable")) {
> > +             ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_PWM,
> > +                                      MT6370_BL_PWM_EN_MASK,
> > +                                      MT6370_BL_PWM_EN_MASK);
> > +             if (ret)
> > +                     return ret;
> > +     }
>
> As above comment... all of the boolean properties are now being read
> incorrectly.
>
>
> > +
> > +     if (device_property_read_bool(dev, "mediatek,bled-pwm-hys-enable")) {
> > +             ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_PWM,
> > +                                      MT6370_BL_PWM_HYS_EN_MASK,
> > +                                      MT6370_BL_PWM_HYS_EN_MASK);
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +
> > +     ret = device_property_read_u8(dev, "mediatek,bled-pwm-hys-input-bit",
> > +                                   &prop_val);
> > +     if (!ret) {
> > +             val = min_t(u8, prop_val, 3)
> > +                   << (ffs(MT6370_BL_PWM_HYS_SEL_MASK) - 1);
> > +             ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_PWM,
> > +                                      MT6370_BL_PWM_HYS_SEL_MASK, val);
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +
> > +     ret = device_property_read_u8(dev, "mediatek,bled-ovp-microvolt",
> > +                                   &prop_val);
> > +     if (!ret) {
> > +             val = min_t(u8, prop_val, 3)
> > +                   << (ffs(MT6370_BL_OVP_SEL_MASK) - 1);
>
> This has been renamed but still seems to the using 0, 1, 2, 3 rather
> than an actual value in microvolts.

I’m so sorry for using the not actual value in microvolts and microamps.
I will refine these mistakes along with DT in the next patch. Thank you!

>
>
> > +             ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_BSTCTRL,
> > +                                      MT6370_BL_OVP_SEL_MASK, val);
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +
> > +     if (device_property_read_bool(dev, "mediatek,bled-ovp-shutdown")) {
> > +             ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_BSTCTRL,
> > +                                      MT6370_BL_OVP_EN_MASK,
> > +                                      MT6370_BL_OVP_EN_MASK);
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +
> > +     ret = device_property_read_u8(dev, "mediatek,bled-ocp-microamp",
> > +                                   &prop_val);
> > +     if (!ret) {
> > +             val = min_t(u8, prop_val, 3)
> > +                   << (ffs(MT6370_BL_OC_SEL_MASK) - 1);
>
> Likewise, should this be accepting a value in microamps?
>
>
> > +             ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_BSTCTRL,
> > +                                      MT6370_BL_OC_SEL_MASK, val);
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +
> > +     if (device_property_read_bool(dev, "mediatek,bled-ocp-shutdown")) {
> > +             ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_BSTCTRL,
> > +                                      MT6370_BL_OC_EN_MASK,
> > +                                      MT6370_BL_OC_EN_MASK);
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +
> > +     /* Common properties */
> > +     ret = device_property_read_u32(dev, "max-brightness", &brightness);
> > +     if (ret)
> > +             brightness = MT6370_BL_MAX_BRIGHTNESS;
> > +
> > +     props->max_brightness = min_t(u32, brightness,
> > +                                   MT6370_BL_MAX_BRIGHTNESS);
> > +
> > +     ret = device_property_read_u32(dev, "default-brightness", &brightness);
> > +     if (ret)
> > +             brightness = props->max_brightness;
> > +
> > +     props->brightness = min_t(u32, brightness, props->max_brightness);
> > +
> > +
> > +     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 (ch_val:%d)\n", prop_val);
>
> Error string has not been updated to match condition that triggers it.
>

I will refine this wrong error string in the next patch, thanks!

>
> > +             return -EINVAL;
> > +     }
>
>
> Daniel.

Best regards,
ChiaEn Wu