Re: [PATCH v4] leds: max597x: Add support for max597x

[Naresh Solanki]

Hi Pavel,

On 13-04-2023 04:43 pm, Pavel Machek wrote:
> Hi!
>
> > From: Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx>
> >
> > max597x is hot swap controller with indicator LED support.
> > This driver uses DT property to configure led during boot time &
> > also provide the LED control in sysfs.
> >
> > DTS example:
> >      i2c {
> >          #address-cells = <1>;
> >          #size-cells = <0>;
> >          regulator@3a {
> >              compatible = "maxim,max5978";
> >              reg = <0x3a>;
> >              vss1-supply = <&p3v3>;
> >
> >              regulators {
> >                  sw0_ref_0: sw0 {
> >                      shunt-resistor-micro-ohms = <12000>;
> >                  };
> >              };
> >
> >              leds {
> >                  #address-cells = <1>;
> >                  #size-cells = <0>;
> >                  led@0 {
> >                      reg = <0>;
> >                      label = "led0";
> >                      default-state = "on";
> >                  };
> >                  led@1 {
> >                      reg = <1>;
> >                      label = "led1";
> >                      default-state = "on";
> >                  };
> >              };
> >          };
> >      };
>
> Yeah, well, dts bindings need to be properly documented, and example
> goes to the binding, right?
Yes.
> Plus, we should have better names than led0/led1. Something like
> hdd0:green:something, based on what the LED does and what are you hot
> swapping. See/modify Documentation/leds/well-known-leds.txt .
Yeah sure.
> > +static int max597x_led_set_brightness(struct led_classdev *cdev,
> > +				      enum led_brightness brightness)
> > +{
> > +	struct max597x_led *ddata = ldev_to_maxled(cdev);
> > +	int ret, val;
> > +
> > +	if (!ddata->regmap)
> > +		return -ENODEV;
> > +
> > +	/* Set/Clear corresponding bit for given led index */
>
> "/clear".
Ack.
> > +	val = !brightness ? BIT(ddata->index) : 0;
> > +	ret = regmap_update_bits(ddata->regmap, MAX5970_REG_LED_FLASH, BIT(ddata->index), val);
> > +	if (ret < 0)
> > +		dev_err(cdev->dev, "failed to set brightness %d", ret);
>
> '\n"'.
Ack
> > +	ddata->cdev.brightness_set_blocking = max597x_led_set_brightness;
> > +	ddata->cdev.default_trigger = "none";
>
> So what do these leds normally do? Should they be registered with
> common function to handle default triggers etc?
Not sure if I understand your question right. In my use case in server 
motherboards, they are use to indicate presence of power for individual 
PCIe NVME connectors. Turning the LED on/off is handled by another 
application based on some conditions.
> > +	ddata->index = reg;
> > +	ddata->regmap = regmap;
> > +	ret = devm_led_classdev_register(dev, &ddata->cdev);
> > +	if (ret)
> > +		dev_err(dev, "Error initializing LED %s", ddata->cdev.name);
>
> '\n"'.
Ack
> > +module_platform_driver(max597x_led_driver);
> > +MODULE_AUTHOR("Patrick Rudolph <patrick.rudolph@xxxxxxxxxxxxx>");
> > +MODULE_DESCRIPTION("MAX5970_hot-swap controller LED driver");
>
> "MAX5970 hot-swap"?
max5970 is primarily a hotswap controller & it also had indication led 
support.
> > +MODULE_LICENSE("GPL");
> >
> > base-commit: 11e572d06c23d61683e20a98bd16f550ef17ac65
> > prerequisite-patch-id: 456044abe991b2ff3b521d337825432789d71b29
>
> ?? Send prerequisites in the series?
Will fix in v5.
> BR,
> 								Pavel
Regards,
Naresh