| Message ID | 20230323194550.1914725-2-Naresh.Solanki@9elements.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | None | expand |
Hi, On 24-03-2023 09:06 pm, Christophe JAILLET wrote: > Le 24/03/2023 à 11:54, Naresh Solanki a écrit : >> Hi, >> >> On 24-03-2023 01:48 am, Christophe JAILLET wrote: >>> Le 23/03/2023 à 20:45, Naresh Solanki a écrit : >>>> From: Patrick Rudolph <patrick.rudolph@9elements.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. >>>> > > [...] > > >>>> +static int max597x_led_probe(struct platform_device *pdev) >>>> +{ >>>> + struct device_node *np = dev_of_node(pdev->dev.parent); >>>> + struct regmap *regmap = dev_get_regmap(pdev->dev.parent, NULL); >>>> + struct device_node *led_node; >>>> + struct device_node *child; >>>> + int ret = 0; >>>> + >>>> + if (!regmap) >>>> + return -EPROBE_DEFER; >>>> + >>>> + led_node = of_get_child_by_name(np, "leds"); >>>> + if (!led_node) >>>> + return -ENODEV; >>>> + >>>> + 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) >>>> + of_node_put(child); >>> >>> This of_node_put() looks odd to me. >> Not sure if I get this right but if led setup fails of_node_put should >> be called. > > My understanding is that this of_node_put() is there in case of error, > to release what would otherwise never be released by > for_each_available_child_of_node() if we exit early from the loop. > > If the purpose is to release a reference taken in max597x_setup_led() in > case of error: > - this should be done IMHO within max597x_setup_led() directly > - there should be a of_node_get() somewhere in max597x_setup_led() > (after: > if (of_property_read_string(nc, "label", &led->led.name)) > led->led.name = nc->name; > + error handling path, *or* > just before the final return ret; when we know that everything is > fine, > if I understand correctly the code) > > Is the reference taken elsewhere? > Did I miss something obvious? > > One of the reference is "drivers/leds/leds-sc27xx-bltc.c" line 311 Please do let me know if I have to do anything about it. >>> "return ret;" or "break;" missing ? >>> >> Didn't add a break so that it can continue initializing remaining led >> if any. > > Ok. Don't know the code enough to see if correct or not, but based on my > comment above, I think that something is missing in max597x_setup_led() > and that errors should be silently ignored here. In my implementation, I have chosen to continue with the next LED if an error occurs, rather than aborting the 'for loop' with an error. I have seen other implementations also done in a similar way. Do you have any further inputs or suggestions on this approach. > > CJ > >>>> + } >>>> + >>>> + return ret; >>>> +} >>>> + > > [...] > Regards, Naresh
Le 27/03/2023 à 17:47, Naresh Solanki a écrit : > Hi, > > On 24-03-2023 09:06 pm, Christophe JAILLET wrote: >> Le 24/03/2023 à 11:54, Naresh Solanki a écrit : >>> Hi, >>> >>> On 24-03-2023 01:48 am, Christophe JAILLET wrote: >>>> Le 23/03/2023 à 20:45, Naresh Solanki a écrit : >>>>> From: Patrick Rudolph <patrick.rudolph@9elements.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. >>>>> >> >> [...] >> >> >>>>> +static int max597x_led_probe(struct platform_device *pdev) >>>>> +{ >>>>> + struct device_node *np = dev_of_node(pdev->dev.parent); >>>>> + struct regmap *regmap = dev_get_regmap(pdev->dev.parent, NULL); >>>>> + struct device_node *led_node; >>>>> + struct device_node *child; >>>>> + int ret = 0; >>>>> + >>>>> + if (!regmap) >>>>> + return -EPROBE_DEFER; >>>>> + >>>>> + led_node = of_get_child_by_name(np, "leds"); >>>>> + if (!led_node) >>>>> + return -ENODEV; >>>>> + >>>>> + 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) >>>>> + of_node_put(child); >>>> >>>> This of_node_put() looks odd to me. >>> Not sure if I get this right but if led setup fails of_node_put >>> should be called. >> >> My understanding is that this of_node_put() is there in case of error, >> to release what would otherwise never be released by >> for_each_available_child_of_node() if we exit early from the loop. >> >> If the purpose is to release a reference taken in max597x_setup_led() >> in case of error: >> - this should be done IMHO within max597x_setup_led() directly >> - there should be a of_node_get() somewhere in max597x_setup_led() >> (after: >> if (of_property_read_string(nc, "label", &led->led.name)) >> led->led.name = nc->name; >> + error handling path, *or* >> just before the final return ret; when we know that everything >> is fine, >> if I understand correctly the code) >> >> Is the reference taken elsewhere? >> Did I miss something obvious? >> >> > One of the reference is "drivers/leds/leds-sc27xx-bltc.c" line 311 > Please do let me know if I have to do anything about it. By reference, I was speaking of reference taken by a of_node_get() call and released by a of_node_put() call. Anyway, I do agree with leds-sc27xx-bltc.c. There is a of_node_put() because for_each_available_child_of_node() won't be able to do it by itself *in case of early return* ("return err;") In all other paths (when the loop goes to the end), the reference taken by for_each_available_child_of_node() is also released, on the next iteration, by for_each_available_child_of_node(). In *your* case, if you don't break or return, there is no need to call of_node_put() explicitly. It would lead to a double put. (yours and the one that will be done by for_each_available_child_of_node()). Have a look at for_each_available_child_of_node() and more specifically at of_get_next_available_child(). At the first call 'child' is NULL. A ref is taken [1]. Nothing is released. For following calls, a new ref is taken on a new node [1], and the previous reference is released [2]. On the last call, the 'for' loop will not be executed because there is nothing to scan anymore. No new reference is taken, and the previous (and last) refence is finally released [2]. [1]: https://elixir.bootlin.com/linux/v6.3-rc3/source/drivers/of/base.c#L808 [2]: https://elixir.bootlin.com/linux/v6.3-rc3/source/drivers/of/base.c#L811 > >>>> "return ret;" or "break;" missing ? >>>> >>> Didn't add a break so that it can continue initializing remaining led >>> if any. >> >> Ok. Don't know the code enough to see if correct or not, but based on >> my comment above, I think that something is missing in >> max597x_setup_led() and that errors should be silently ignored here. > In my implementation, I have chosen to continue with the next LED if an > error occurs, rather than aborting the 'for loop' with an error. I have > seen other implementations also done in a similar way. > Do you have any further inputs or suggestions on this approach. No, sorry, I won't be of any help on what design is the best. CJ
Hi, On 27-03-2023 10:50 pm, Christophe JAILLET wrote: > Le 27/03/2023 à 17:47, Naresh Solanki a écrit : >> Hi, >> >> On 24-03-2023 09:06 pm, Christophe JAILLET wrote: >>> Le 24/03/2023 à 11:54, Naresh Solanki a écrit : >>>> Hi, >>>> >>>> On 24-03-2023 01:48 am, Christophe JAILLET wrote: >>>>> Le 23/03/2023 à 20:45, Naresh Solanki a écrit : >>>>>> From: Patrick Rudolph <patrick.rudolph@9elements.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. >>>>>> >>> >>> [...] >>> >>> >>>>>> +static int max597x_led_probe(struct platform_device *pdev) >>>>>> +{ >>>>>> + struct device_node *np = dev_of_node(pdev->dev.parent); >>>>>> + struct regmap *regmap = dev_get_regmap(pdev->dev.parent, NULL); >>>>>> + struct device_node *led_node; >>>>>> + struct device_node *child; >>>>>> + int ret = 0; >>>>>> + >>>>>> + if (!regmap) >>>>>> + return -EPROBE_DEFER; >>>>>> + >>>>>> + led_node = of_get_child_by_name(np, "leds"); >>>>>> + if (!led_node) >>>>>> + return -ENODEV; >>>>>> + >>>>>> + 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) >>>>>> + of_node_put(child); >>>>> >>>>> This of_node_put() looks odd to me. >>>> Not sure if I get this right but if led setup fails of_node_put >>>> should be called. >>> >>> My understanding is that this of_node_put() is there in case of >>> error, to release what would otherwise never be released by >>> for_each_available_child_of_node() if we exit early from the loop. >>> >>> If the purpose is to release a reference taken in max597x_setup_led() >>> in case of error: >>> - this should be done IMHO within max597x_setup_led() directly >>> - there should be a of_node_get() somewhere in max597x_setup_led() >>> (after: >>> if (of_property_read_string(nc, "label", &led->led.name)) >>> led->led.name = nc->name; >>> + error handling path, *or* >>> just before the final return ret; when we know that everything >>> is fine, >>> if I understand correctly the code) >>> >>> Is the reference taken elsewhere? >>> Did I miss something obvious? >>> >>> >> One of the reference is "drivers/leds/leds-sc27xx-bltc.c" line 311 >> Please do let me know if I have to do anything about it. > By reference, I was speaking of reference taken by a of_node_get() call > and released by a of_node_put() call. > > Anyway, I do agree with leds-sc27xx-bltc.c. > There is a of_node_put() because for_each_available_child_of_node() > won't be able to do it by itself *in case of early return* ("return err;") > > In all other paths (when the loop goes to the end), the reference taken > by for_each_available_child_of_node() is also released, on the next > iteration, by for_each_available_child_of_node(). > > In *your* case, if you don't break or return, there is no need to call > of_node_put() explicitly. It would lead to a double put. (yours and the > one that will be done by for_each_available_child_of_node()). > > Have a look at for_each_available_child_of_node() and more specifically > at of_get_next_available_child(). > > At the first call 'child' is NULL. A ref is taken [1]. Nothing is released. > For following calls, a new ref is taken on a new node [1], and the > previous reference is released [2]. > On the last call, the 'for' loop will not be executed because there is > nothing to scan anymore. No new reference is taken, and the previous > (and last) refence is finally released [2]. Yes you are right. That of_node_put would be duplicate as it is already taken care by the for loop. Will remove that in next revision. > > > [1]: > https://elixir.bootlin.com/linux/v6.3-rc3/source/drivers/of/base.c#L808 > [2]: > https://elixir.bootlin.com/linux/v6.3-rc3/source/drivers/of/base.c#L811 > >> >>>>> "return ret;" or "break;" missing ? >>>>> >>>> Didn't add a break so that it can continue initializing remaining >>>> led if any. >>> >>> Ok. Don't know the code enough to see if correct or not, but based on >>> my comment above, I think that something is missing in >>> max597x_setup_led() and that errors should be silently ignored here. >> In my implementation, I have chosen to continue with the next LED if >> an error occurs, rather than aborting the 'for loop' with an error. I >> have seen other implementations also done in a similar way. >> Do you have any further inputs or suggestions on this approach. > > No, sorry, I won't be of any help on what design is the best. > > CJ > Regards, Naresh
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig index 9dbce09eabac..ec2b731ae545 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 597x smart switch indication LEDs + via the I2C bus. + + To compile this driver as a module, choose M here: the module will + be called max597x-led. + 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..3e1747c8693e --- /dev/null +++ b/drivers/leds/leds-max597x.c @@ -0,0 +1,112 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Device driver for leds in MAX5970 and MAX5978 IC + * + * Copyright (c) 2022 9elements GmbH + * + * Author: Patrick Rudolph <patrick.rudolph@9elements.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, led) + +struct max597x_led { + struct regmap *regmap; + struct led_classdev led; + unsigned int index; +}; + +static int max597x_led_set_brightness(struct led_classdev *cdev, + enum led_brightness brightness) +{ + struct max597x_led *led = ldev_to_maxled(cdev); + int ret, val = 0; + + if (!led || !led->regmap) + return -ENODEV; + + val = !brightness ? BIT(led->index) : 0; + ret = regmap_update_bits(led->regmap, MAX5970_REG_LED_FLASH, BIT(led->index), val); + if (ret < 0) + dev_err(cdev->dev, "failed to set brightness %d\n", ret); + return ret; +} + +static int max597x_setup_led(struct device *dev, struct regmap *regmap, struct device_node *nc, + u32 reg) +{ + struct max597x_led *led; + int ret = 0; + + led = devm_kzalloc(dev, sizeof(struct max597x_led), + GFP_KERNEL); + if (!led) + return -ENOMEM; + + if (of_property_read_string(nc, "label", &led->led.name)) + led->led.name = nc->name; + + led->led.max_brightness = 1; + led->led.brightness_set_blocking = max597x_led_set_brightness; + led->led.default_trigger = "none"; + led->index = reg; + led->regmap = regmap; + ret = led_classdev_register(dev, &led->led); + if (ret) + dev_err(dev, "Error in initializing led %s", led->led.name); + + return ret; +} + +static int max597x_led_probe(struct platform_device *pdev) +{ + struct device_node *np = dev_of_node(pdev->dev.parent); + struct regmap *regmap = dev_get_regmap(pdev->dev.parent, NULL); + struct device_node *led_node; + struct device_node *child; + int ret = 0; + + if (!regmap) + return -EPROBE_DEFER; + + led_node = of_get_child_by_name(np, "leds"); + if (!led_node) + return -ENODEV; + + 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) + of_node_put(child); + } + + 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@9elements.com>"); +MODULE_DESCRIPTION("MAX5970_hot-swap controller driver"); +MODULE_LICENSE("GPL");