Re: [PATCH v6 11/13] leds: rgb: mt6370: Add MediaTek MT6370 current sink type LED Indicator support

[szuni chen <szunichen@gmail.com>]

Hi Pavel,
Sorry for resending the mail, I add all reviewers this time.


Pavel Machek <pavel@ucw.cz> 於 2022年7月31日 週日 清晨5:39寫道：
>
> Hi!
>
...

>
> > +config LEDS_MT6370_RGB
> > +     tristate "LED Support for MediaTek MT6370 PMIC"
> > +     depends on MFD_MT6370
> > +     select LINEAR_RANGE
> > +     help
> > +       Say Y here to enable support for MT6370_RGB LED device.
> > +       In MT6370, there are four channel current-sink LED drivers that
> > +       support hardware pattern for constant current, PWM, and breath mode.
>
>
> > +       Isink4 channel can also be used as a CHG_VIN power good  indicator.
>
> That does not really belong here.
>
Should we just remove it, or describe Isink4 in another position?

> > +struct mt6370_priv {
> > +     /* Per LED access lock */
> > +     struct mutex lock;
>
> Do we really need per-led locking?
>
Sorry, maybe the comment is not precise.
The lock is used to prevent LEDs from accessing the HW at the same time.

If I use
/* LED access lock, only one LED can access the HW at the same time */
will it look better?
No, we aren't.
There are six steps tr1, tr2, tf1, tf2, ton, and toff in MT6370 led breath mode.
We parse duration settings from node "hw_pattern" and set them to the registers.

This function is used to generate duration settings from hw_pattern.

The brightness of the six steps mentioned above in breath mode is
limited to the node "brightness".
The target brightness of tr1 and tf1 is 25% of node "brightness", and
they are automatically set by HW.

> > +static int mt6370_init_led_properties(struct mt6370_led *led,
> > +                                   struct led_init_data *init_data)
> > +{
> > +     struct mt6370_priv *priv = led->priv;
> > +     struct device *dev = priv->dev;
> > +     struct led_classdev *lcdev;
> > +     struct fwnode_handle *child;
> > +     enum mt6370_led_ranges sel_range;
> > +     u32 max_uA, max_level;
> > +     const char * const states[] = { "off", "keep", "on" };
>
> We'd really preffer not to add "keep" / "on" support unless you need
> it.
>
Forgive me, but I would like to know why "keep" / "on" is not preferred.
We think the users might have some conditions that need them.


Best Regards,
Alice

Pavel Machek <pavel@ucw.cz> 於 2022年7月31日 週日 清晨5:39寫道：
>
> Hi!
>
> > From: ChiYuan Huang <cy_huang@richtek.com>
> >
> > The MediaTek MT6370 is a highly-integrated smart power management IC,
> > which includes a single cell Li-Ion/Li-Polymer switching battery
> > charger, a USB Type-C & Power Delivery (PD) controller, dual
> > Flash LED current sources, a RGB LED driver, a backlight WLED driver,
> > a display bias driver and a general LDO for portable devices.
> >
> > In MediaTek MT6370, there are four channel current-sink RGB LEDs that
> > support hardware pattern for constant current, PWM, and breath mode.
> > Isink4 channel can also be used as a CHG_VIN power good indicator.
> >
>
> > +config LEDS_MT6370_RGB
> > +     tristate "LED Support for MediaTek MT6370 PMIC"
> > +     depends on MFD_MT6370
> > +     select LINEAR_RANGE
> > +     help
> > +       Say Y here to enable support for MT6370_RGB LED device.
> > +       In MT6370, there are four channel current-sink LED drivers that
> > +       support hardware pattern for constant current, PWM, and breath mode.
>
>
> > +       Isink4 channel can also be used as a CHG_VIN power good  indicator.
>
> That does not really belong here.
>
> > +struct mt6370_priv {
> > +     /* Per LED access lock */
> > +     struct mutex lock;
>
> Do we really need per-led locking?
>
> > +static int mt6370_gen_breath_pattern(struct mt6370_priv *priv,
> > +                                  struct led_pattern *pattern, u32 len,
> > +                                  u8 *pattern_val, u32 val_len)
> > +{
> > +     enum mt6370_led_ranges sel_range;
> > +     struct led_pattern *curr;
> > +     unsigned int sel;
> > +     u8 val[P_MAX_PATTERNS / 2] = {};
> > +     int i;
> > +
> > +     if (len < P_MAX_PATTERNS && val_len < P_MAX_PATTERNS / 2)
> > +             return -EINVAL;
> > +
> > +     /*
> > +      * Pattern list
> > +      * tr1: byte 0, b'[7: 4]
> > +      * tr2: byte 0, b'[3: 0]
> > +      * tf1: byte 1, b'[7: 4]
> > +      * tf2: byte 1, b'[3: 0]
> > +      * ton: byte 2, b'[7: 4]
> > +      * toff: byte 2, b'[3: 0]
> > +      */
> > +     for (i = 0; i < P_MAX_PATTERNS; i++) {
> > +             curr = pattern + i;
> > +
> > +             sel_range = i == P_LED_TOFF ? R_LED_TOFF : R_LED_TRFON;
> > +
> > +             linear_range_get_selector_within(priv->ranges + sel_range,
> > +                                              curr->delta_t, &sel);
> > +
> > +             val[i / 2] |= sel << (4 * ((i + 1) % 2));
> > +     }
> > +
> > +     memcpy(pattern_val, val, 3);
> > +
> > +     return 0;
> > +}
>
> I wonder how this works... you are not creating private sysfs
> interface, are you?
>
> > +static int mt6370_init_led_properties(struct mt6370_led *led,
> > +                                   struct led_init_data *init_data)
> > +{
> > +     struct mt6370_priv *priv = led->priv;
> > +     struct device *dev = priv->dev;
> > +     struct led_classdev *lcdev;
> > +     struct fwnode_handle *child;
> > +     enum mt6370_led_ranges sel_range;
> > +     u32 max_uA, max_level;
> > +     const char * const states[] = { "off", "keep", "on" };
>
> We'd really preffer not to add "keep" / "on" support unless you need
> it.
>
> > +                     if (ret)
> > +                             return dev_err_probe(dev, ret,
> > +                                                  "led %d, no color specified\n",
> > +                                                  led->index);
>
> led->LED.
>
> > +             if (num_color < 2)
> > +                     return dev_err_probe(dev, -EINVAL,
> > +                                          "Multicolor must include
> > 2 or more led channel\n");
>
> "LED channels".
>
> > +static int mt6370_isnk_init_default_state(struct mt6370_led *led)
> > +{
> > +     struct mt6370_priv *priv = led->priv;
> > +     unsigned int enable, level;
> > +     int ret;
> > +
> > +     ret = mt6370_get_led_brightness(priv, led->index, &level);
> > +     if (ret)
> > +             return ret;
> > +
> > +     ret = regmap_field_read(priv->fields[F_RGB_EN], &enable);
> > +     if (ret)
> > +             return ret;
> > +
> > +     if (!(enable & MT6370_CHEN_BIT(led->index)))
> > +             level = LED_OFF;
>
> Just use 0 instead of LED_OFF.
>
> Best regards,
>                                                         Pavel
>
> --
> People of Russia, stop Putin before his war on Ukraine escalates.