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Message-ID: <20230420135428.GD996918@google.com>
Date: Thu, 20 Apr 2023 14:54:28 +0100
From: Lee Jones <lee@...nel.org>
To: Naresh Solanki <naresh.solanki@...ements.com>
Cc: Pavel Machek <pavel@....cz>,
Patrick Rudolph <patrick.rudolph@...ements.com>,
linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org
Subject: Re: [PATCH v5] leds: max597x: Add support for max597x
On Thu, 20 Apr 2023, Naresh Solanki wrote:
> Hi Lee,
>
> On 20-04-2023 05:20 pm, Lee Jones wrote:
> > On Mon, 17 Apr 2023, Naresh Solanki wrote:
> >
> > > From: Patrick Rudolph <patrick.rudolph@...ements.com>
> > >
> > > 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 = "ssd0:green";
> > > default-state = "on";
> > > };
> > > led@1 {
> > > reg = <1>;
> > > label = "ssd1:green";
> > > default-state = "on";
> > > };
> > > };
> > > };
> > > };
> >
> > Where is the DT binding document for this?
? <---------------------------------------------------------------------------
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
> > > Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
> > > ...
> > > Changes in V5:
> > > - Update commit message
> > > - Fix comments
> > > - Add necessary new line
> > > Changes in V4:
> > > - Remove unwanted preinitialise
> > > - Remove unneeded line breaks
> > > - Fix variable name to avoid confusion
> > > - Update module description to mention LED driver.
> > > Changes in V3:
> > > - Remove of_node_put as its handled by for loop
> > > - Print error if an LED fails to register.
> > > - Update driver name in Kconfig description
> > > - Remove unneeded variable assignment
> > > - Use devm_led_classdev_register to reget led
> > > Changes in V2:
> > > - Fix regmap update
> > > - Remove devm_kfree
> > > - Remove default-state
> > > - Add example dts in commit message
> > > - Fix whitespace in Kconfig
> > > - Fix comment
> > > ---
> > > drivers/leds/Kconfig | 11 ++++
> > > drivers/leds/Makefile | 1 +
> > > drivers/leds/leds-max597x.c | 115 ++++++++++++++++++++++++++++++++++++
> > > 3 files changed, 127 insertions(+)
> > > create mode 100644 drivers/leds/leds-max597x.c
> > >
> > > diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> > > index 9dbce09eabac..60004cb8c257 100644
> > > --- a/drivers/leds/Kconfig
> > > +++ b/drivers/leds/Kconfig
> > > @@ -590,6 +590,17 @@ config LEDS_ADP5520
> > > To compile this driver as a module, choose M here: the module will
> > > be called leds-adp5520.
> > > +config LEDS_MAX597X
> > > + tristate "LED Support for Maxim 597x"
> > > + depends on LEDS_CLASS
> > > + depends on MFD_MAX597X
> > > + help
> > > + This option enables support for the Maxim MAX5970 & MAX5978 smart
> > > + switch indication LEDs via the I2C bus.
> > > +
> > > + To compile this driver as a module, choose M here: the module will
> > > + be called leds-max597x.
> > > +
> > > config LEDS_MC13783
> > > tristate "LED Support for MC13XXX PMIC"
> > > depends on LEDS_CLASS
> > > diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> > > index d30395d11fd8..da1192e40268 100644
> > > --- a/drivers/leds/Makefile
> > > +++ b/drivers/leds/Makefile
> > > @@ -53,6 +53,7 @@ obj-$(CONFIG_LEDS_LP8501) += leds-lp8501.o
> > > obj-$(CONFIG_LEDS_LP8788) += leds-lp8788.o
> > > obj-$(CONFIG_LEDS_LP8860) += leds-lp8860.o
> > > obj-$(CONFIG_LEDS_LT3593) += leds-lt3593.o
> > > +obj-$(CONFIG_LEDS_MAX597X) += leds-max597x.o
> > > obj-$(CONFIG_LEDS_MAX77650) += leds-max77650.o
> > > obj-$(CONFIG_LEDS_MAX8997) += leds-max8997.o
> > > obj-$(CONFIG_LEDS_MC13783) += leds-mc13783.o
> > > diff --git a/drivers/leds/leds-max597x.c b/drivers/leds/leds-max597x.c
> > > new file mode 100644
> > > index 000000000000..edbd43018822
> > > --- /dev/null
> > > +++ b/drivers/leds/leds-max597x.c
> > > @@ -0,0 +1,115 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Device driver for leds in MAX5970 and MAX5978 IC
> >
> > "MAX5970 and MAX5978 IC LED support"
> >
> > > + * Copyright (c) 2022 9elements GmbH
> > > + *
> > > + * Author: Patrick Rudolph <patrick.rudolph@...ements.com>
> > > + */
> > > +
> > > +#include <linux/leds.h>
> > > +#include <linux/mfd/max597x.h>
> > > +#include <linux/of.h>
> > > +#include <linux/platform_device.h>
> > > +#include <linux/regmap.h>
> > > +
> > > +#define ldev_to_maxled(c) container_of(c, struct max597x_led, cdev)
> > > +
> > > +struct max597x_led {
> > > + struct regmap *regmap;
> > > + struct led_classdev cdev;
> > > + unsigned int index;
> > > +};
> > > +
> > > +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 */
> > > + 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);
> > > +
> > > + return ret;
> > > +}
> > > +
> > > +static int max597x_setup_led(struct device *dev, struct regmap *regmap, struct device_node *nc,
> > > + u32 reg)
> > > +{
> > > + struct max597x_led *ddata;
> > > + int ret;
> > > +
> > > + ddata = devm_kzalloc(dev, sizeof(struct max597x_led), GFP_KERNEL);
> > > + if (!ddata)
> > > + return -ENOMEM;
> > > +
> > > + if (of_property_read_string(nc, "label", &ddata->cdev.name))
> > > + ddata->cdev.name = nc->name;
> > > +
> > > + ddata->cdev.max_brightness = 1;
> > > + ddata->cdev.brightness_set_blocking = max597x_led_set_brightness;
> > > + ddata->cdev.default_trigger = "none";
> > > + 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);
> > > +
> > > + return ret;
> > > +}
> > > +
> > > +static int max597x_led_probe(struct platform_device *pdev)
> > > +{
> > > + struct device_node *np = dev_of_node(pdev->dev.parent);
> >
> > My previous question about having its own compatible string was ignored.
> As previously stated, the MFD driver for max597x already has a compatible
> string that serves its purpose, so I opted not to include a separate
> compatible string for the leaf driver.
> Prior to implementing this approach, I reviewed other implementations within
> the MFD driver, such as the sy7636 which uses the similar approach in leaf
> driver.
I'm not saying it's never been done. However, most of the time
leaf/child devices have their own compatible string and node.
> > > + struct regmap *regmap;
> > > + struct device_node *led_node;
> > > + struct device_node *child;
> > > + int ret = 0;
> > > +
> > > + regmap = dev_get_regmap(pdev->dev.parent, NULL);
> > > + if (!regmap)
> > > + return -EPROBE_DEFER;
Will other child devices have be using the parent's regmap too?
> > > + led_node = of_get_child_by_name(np, "leds");
> > > + if (!led_node)
> > > + return -ENODEV;
It's odd for a device to be referring to itself as the "child".
> > > + for_each_available_child_of_node(led_node, child) {
> > > + u32 reg;
> > > +
> > > + if (of_property_read_u32(child, "reg", ®))
> > > + continue;
> > > +
> > > + if (reg >= MAX597X_NUM_LEDS) {
> > > + dev_err(&pdev->dev, "invalid LED (%u >= %d)\n", reg,
> > > + MAX597X_NUM_LEDS);
> > > + continue;
> > > + }
> > > +
> > > + ret = max597x_setup_led(&pdev->dev, regmap, child, reg);
> > > + if (ret < 0)
> > > + dev_err(&pdev->dev, "Failed to initialize LED %u\n", reg);
> >
> > You've ignored my previous review.
> I would like to clarify that I did not intend to overlook your previous
> review comment. Rather, I have taken it into consideration and evaluated it
> in the context of the current approach, which is derived from the code in
> other LED drivers.
> To eliminate any potential confusion, it may be best to adopt a consistent
> approach that all LED drivers should adhere to in similar circumstances.
I agree. That's start with this one.
You should not error and continue. If you encounter an error, please
unwind what you have done before and return the error.
> > > + }
> > > +
> > > + return ret;
> > > +}
> > > +
> > > +static struct platform_driver max597x_led_driver = {
> > > + .driver = {
> > > + .name = "max597x-led",
> > > + },
> > > + .probe = max597x_led_probe,
> > > +};
> > > +
> > > +module_platform_driver(max597x_led_driver);
> > > +MODULE_AUTHOR("Patrick Rudolph <patrick.rudolph@...ements.com>");
> > > +MODULE_DESCRIPTION("MAX5970_hot-swap controller LED driver");
> > > +MODULE_LICENSE("GPL");
> > >
> > > base-commit: 9d8d0d98885abba451d7ffc4885236d14ead3c9a
> > > --
> > > 2.39.1
> > >
> >
> Regards,
> Naresh
--
Lee Jones [李琼斯]
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