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Date:   Mon, 26 Apr 2021 13:24:57 +0100
From:   Daniel Thompson <daniel.thompson@linaro.org>
To:     ChiYuan Huang <u0084500@gmail.com>
Cc:     Lee Jones <lee.jones@linaro.org>, lgirdwood@gmail.com,
        Mark Brown <broonie@kernel.org>, jingoohan1@gmail.com,
        b.zolnierkie@samsung.com, Pavel Machek <pavel@ucw.cz>,
        Rob Herring <robh+dt@kernel.org>,
        dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org,
        lkml <linux-kernel@vger.kernel.org>,
        Linux LED Subsystem <linux-leds@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, cy_huang <cy_huang@richtek.com>
Subject: Re: [RESEND PATCH v6 4/4] backlight: rt4831: Adds support for
 Richtek RT4831 backlight
Message-ID: <20210426122457.j4vjvng6bgxbtpjk@maple.lan>
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 <20210426101955.uvuzzsiig27xyuxc@maple.lan>
 <CADiBU39F8+GM4z7xJPpDVS7riPGi02BrurvMmnHMEPeKBQJ_tg@mail.gmail.com>
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On Mon, Apr 26, 2021 at 06:50:15PM +0800, ChiYuan Huang wrote:
> Hi,
> 
> Daniel Thompson <daniel.thompson@linaro.org> 於 2021年4月26日 週一 下午6:19寫道：
> >
> > On Mon, Apr 26, 2021 at 03:18:11PM +0800, cy_huang wrote:
> > > From: ChiYuan Huang <cy_huang@richtek.com>
> > >
> > > Adds support for Richtek RT4831 backlight.
> > >
> > > Signed-off-by: ChiYuan Huang <cy_huang@richtek.com>
> > > Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> > > ---
> > > Resend this v6 patch series to loop devicetree reviewers.
> > >
> > > For next, if the typo in Kconfig 'common' to 'commonly' can be added the below line
> > > Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> > > ---
> >
> > This isn't the best way to handle feedback from multiple maintainers.
> >
> > It is great to see you are keeping track of feedback. However it doesn't
> > make sense to RESEND an old patchset and acknowledge that you haven't
> > fixed a typo yet.
> >
> > It would be better to fix the typo and to resend a v7.
>
> You can refer to the below reply
> https://lkml.org/lkml/2021/4/23/229

Indeed.

However that thread is ambiguous about resending with changes (PATCH v7)
and resending without changes (PATCH RESEND v6). Given you said in March
there was a v7 series coming, I think it would have been better to send a
new version. 

Don't worry about this too much. This is turning into quite a lot of
fuss for a two letter typo. However it's very unusual to send out a
patch (except perhaps an RFC) together with a comment listing what you
need to fix next time around. It is pretty much always better to fix
it first and then send it.


Daniel.


> > >  drivers/video/backlight/Kconfig            |   8 ++
> > >  drivers/video/backlight/Makefile           |   1 +
> > >  drivers/video/backlight/rt4831-backlight.c | 203 +++++++++++++++++++++++++++++
> > >  3 files changed, 212 insertions(+)
> > >  create mode 100644 drivers/video/backlight/rt4831-backlight.c
> > >
> > > diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> > > index d83c87b..de96441 100644
> > > --- a/drivers/video/backlight/Kconfig
> > > +++ b/drivers/video/backlight/Kconfig
> > > @@ -289,6 +289,14 @@ config BACKLIGHT_QCOM_WLED
> > >         If you have the Qualcomm PMIC, say Y to enable a driver for the
> > >         WLED block. Currently it supports PM8941 and PMI8998.
> > >
> > > +config BACKLIGHT_RT4831
> > > +     tristate "Richtek RT4831 Backlight Driver"
> > > +     depends on MFD_RT4831
> > > +     help
> > > +       This enables support for Richtek RT4831 Backlight driver.
> > > +       It's common used to drive the display WLED. There're four channels
> > > +       inisde, and each channel can provide up to 30mA current.
> > > +
> > >  config BACKLIGHT_SAHARA
> > >       tristate "Tabletkiosk Sahara Touch-iT Backlight Driver"
> > >       depends on X86
> > > diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
> > > index 685f3f1..cae2c83 100644
> > > --- a/drivers/video/backlight/Makefile
> > > +++ b/drivers/video/backlight/Makefile
> > > @@ -49,6 +49,7 @@ obj-$(CONFIG_BACKLIGHT_PANDORA)             += pandora_bl.o
> > >  obj-$(CONFIG_BACKLIGHT_PCF50633)     += pcf50633-backlight.o
> > >  obj-$(CONFIG_BACKLIGHT_PWM)          += pwm_bl.o
> > >  obj-$(CONFIG_BACKLIGHT_QCOM_WLED)    += qcom-wled.o
> > > +obj-$(CONFIG_BACKLIGHT_RT4831)               += rt4831-backlight.o
> > >  obj-$(CONFIG_BACKLIGHT_SAHARA)               += kb3886_bl.o
> > >  obj-$(CONFIG_BACKLIGHT_SKY81452)     += sky81452-backlight.o
> > >  obj-$(CONFIG_BACKLIGHT_TOSA)         += tosa_bl.o
> > > diff --git a/drivers/video/backlight/rt4831-backlight.c b/drivers/video/backlight/rt4831-backlight.c
> > > new file mode 100644
> > > index 00000000..42155c7
> > > --- /dev/null
> > > +++ b/drivers/video/backlight/rt4831-backlight.c
> > > @@ -0,0 +1,203 @@
> > > +// SPDX-License-Identifier: GPL-2.0-only
> > > +
> > > +#include <dt-bindings/leds/rt4831-backlight.h>
> > > +#include <linux/backlight.h>
> > > +#include <linux/bitops.h>
> > > +#include <linux/kernel.h>
> > > +#include <linux/module.h>
> > > +#include <linux/platform_device.h>
> > > +#include <linux/property.h>
> > > +#include <linux/regmap.h>
> > > +
> > > +#define RT4831_REG_BLCFG     0x02
> > > +#define RT4831_REG_BLDIML    0x04
> > > +#define RT4831_REG_ENABLE    0x08
> > > +
> > > +#define RT4831_BLMAX_BRIGHTNESS      2048
> > > +
> > > +#define RT4831_BLOVP_MASK    GENMASK(7, 5)
> > > +#define RT4831_BLOVP_SHIFT   5
> > > +#define RT4831_BLPWMEN_MASK  BIT(0)
> > > +#define RT4831_BLEN_MASK     BIT(4)
> > > +#define RT4831_BLCH_MASK     GENMASK(3, 0)
> > > +#define RT4831_BLDIML_MASK   GENMASK(2, 0)
> > > +#define RT4831_BLDIMH_MASK   GENMASK(10, 3)
> > > +#define RT4831_BLDIMH_SHIFT  3
> > > +
> > > +struct rt4831_priv {
> > > +     struct device *dev;
> > > +     struct regmap *regmap;
> > > +     struct backlight_device *bl;
> > > +};
> > > +
> > > +static int rt4831_bl_update_status(struct backlight_device *bl_dev)
> > > +{
> > > +     struct rt4831_priv *priv = bl_get_data(bl_dev);
> > > +     int brightness = backlight_get_brightness(bl_dev);
> > > +     unsigned int enable = brightness ? RT4831_BLEN_MASK : 0;
> > > +     u8 v[2];
> > > +     int ret;
> > > +
> > > +     if (brightness) {
> > > +             v[0] = (brightness - 1) & RT4831_BLDIML_MASK;
> > > +             v[1] = ((brightness - 1) & RT4831_BLDIMH_MASK) >> RT4831_BLDIMH_SHIFT;
> > > +
> > > +             ret = regmap_raw_write(priv->regmap, RT4831_REG_BLDIML, v, sizeof(v));
> > > +             if (ret)
> > > +                     return ret;
> > > +     }
> > > +
> > > +     return regmap_update_bits(priv->regmap, RT4831_REG_ENABLE, RT4831_BLEN_MASK, enable);
> > > +
> > > +}
> > > +
> > > +static int rt4831_bl_get_brightness(struct backlight_device *bl_dev)
> > > +{
> > > +     struct rt4831_priv *priv = bl_get_data(bl_dev);
> > > +     unsigned int val;
> > > +     u8 v[2];
> > > +     int ret;
> > > +
> > > +     ret = regmap_read(priv->regmap, RT4831_REG_ENABLE, &val);
> > > +     if (ret)
> > > +             return ret;
> > > +
> > > +     if (!(val & RT4831_BLEN_MASK))
> > > +             return 0;
> > > +
> > > +     ret = regmap_raw_read(priv->regmap, RT4831_REG_BLDIML, v, sizeof(v));
> > > +     if (ret)
> > > +             return ret;
> > > +
> > > +     ret = (v[1] << RT4831_BLDIMH_SHIFT) + (v[0] & RT4831_BLDIML_MASK) + 1;
> > > +
> > > +     return ret;
> > > +}
> > > +
> > > +static const struct backlight_ops rt4831_bl_ops = {
> > > +     .options = BL_CORE_SUSPENDRESUME,
> > > +     .update_status = rt4831_bl_update_status,
> > > +     .get_brightness = rt4831_bl_get_brightness,
> > > +};
> > > +
> > > +static int rt4831_parse_backlight_properties(struct rt4831_priv *priv,
> > > +                                          struct backlight_properties *bl_props)
> > > +{
> > > +     struct device *dev = priv->dev;
> > > +     u8 propval;
> > > +     u32 brightness;
> > > +     unsigned int val = 0;
> > > +     int ret;
> > > +
> > > +     /* common properties */
> > > +     ret = device_property_read_u32(dev, "max-brightness", &brightness);
> > > +     if (ret)
> > > +             brightness = RT4831_BLMAX_BRIGHTNESS;
> > > +
> > > +     bl_props->max_brightness = min_t(u32, brightness, RT4831_BLMAX_BRIGHTNESS);
> > > +
> > > +     ret = device_property_read_u32(dev, "default-brightness", &brightness);
> > > +     if (ret)
> > > +             brightness = bl_props->max_brightness;
> > > +
> > > +     bl_props->brightness = min_t(u32, brightness, bl_props->max_brightness);
> > > +
> > > +     /* vendor properties */
> > > +     if (device_property_read_bool(dev, "richtek,pwm-enable"))
> > > +             val = RT4831_BLPWMEN_MASK;
> > > +
> > > +     ret = regmap_update_bits(priv->regmap, RT4831_REG_BLCFG, RT4831_BLPWMEN_MASK, val);
> > > +     if (ret)
> > > +             return ret;
> > > +
> > > +     ret = device_property_read_u8(dev, "richtek,bled-ovp-sel", &propval);
> > > +     if (ret)
> > > +             propval = RT4831_BLOVPLVL_21V;
> > > +
> > > +     propval = min_t(u8, propval, RT4831_BLOVPLVL_29V);
> > > +     ret = regmap_update_bits(priv->regmap, RT4831_REG_BLCFG, RT4831_BLOVP_MASK,
> > > +                              propval << RT4831_BLOVP_SHIFT);
> > > +     if (ret)
> > > +             return ret;
> > > +
> > > +     ret = device_property_read_u8(dev, "richtek,channel-use", &propval);
> > > +     if (ret) {
> > > +             dev_err(dev, "richtek,channel-use DT property missing\n");
> > > +             return ret;
> > > +     }
> > > +
> > > +     if (!(propval & RT4831_BLCH_MASK)) {
> > > +             dev_err(dev, "No channel specified\n");
> > > +             return -EINVAL;
> > > +     }
> > > +
> > > +     return regmap_update_bits(priv->regmap, RT4831_REG_ENABLE, RT4831_BLCH_MASK, propval);
> > > +}
> > > +
> > > +static int rt4831_bl_probe(struct platform_device *pdev)
> > > +{
> > > +     struct rt4831_priv *priv;
> > > +     struct backlight_properties bl_props = { .type = BACKLIGHT_RAW,
> > > +                                              .scale = BACKLIGHT_SCALE_LINEAR };
> > > +     int ret;
> > > +
> > > +     priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> > > +     if (!priv)
> > > +             return -ENOMEM;
> > > +
> > > +     priv->dev = &pdev->dev;
> > > +
> > > +     priv->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> > > +     if (!priv->regmap) {
> > > +             dev_err(&pdev->dev, "Failed to init regmap\n");
> > > +             return -ENODEV;
> > > +     }
> > > +
> > > +     ret = rt4831_parse_backlight_properties(priv, &bl_props);
> > > +     if (ret) {
> > > +             dev_err(&pdev->dev, "Failed to parse backlight properties\n");
> > > +             return ret;
> > > +     }
> > > +
> > > +     priv->bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev, priv,
> > > +                                               &rt4831_bl_ops, &bl_props);
> > > +     if (IS_ERR(priv->bl)) {
> > > +             dev_err(&pdev->dev, "Failed to register backlight\n");
> > > +             return PTR_ERR(priv->bl);
> > > +     }
> > > +
> > > +     backlight_update_status(priv->bl);
> > > +     platform_set_drvdata(pdev, priv);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +static int rt4831_bl_remove(struct platform_device *pdev)
> > > +{
> > > +     struct rt4831_priv *priv = platform_get_drvdata(pdev);
> > > +     struct backlight_device *bl_dev = priv->bl;
> > > +
> > > +     bl_dev->props.brightness = 0;
> > > +     backlight_update_status(priv->bl);
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +static const struct of_device_id __maybe_unused rt4831_bl_of_match[] = {
> > > +     { .compatible = "richtek,rt4831-backlight", },
> > > +     {}
> > > +};
> > > +MODULE_DEVICE_TABLE(of, rt4831_bl_of_match);
> > > +
> > > +static struct platform_driver rt4831_bl_driver = {
> > > +     .driver = {
> > > +             .name = "rt4831-backlight",
> > > +             .of_match_table = rt4831_bl_of_match,
> > > +     },
> > > +     .probe = rt4831_bl_probe,
> > > +     .remove = rt4831_bl_remove,
> > > +};
> > > +module_platform_driver(rt4831_bl_driver);
> > > +
> > > +MODULE_AUTHOR("ChiYuan Huang <cy_huang@richtek.com>");
> > > +MODULE_LICENSE("GPL v2");
> > > --
> > > 2.7.4
> > >