Hi Andy, On 20/8/2020 6:52 pm, Andy Shevchenko wrote: > On Thu, Aug 20, 2020 at 12:50:46PM +0800, Rahul Tanwar wrote: >> Intel Lightning Mountain(LGM) SoC contains a PWM fan controller. >> This PWM controller does not have any other consumer, it is a >> dedicated PWM controller for fan attached to the system. Add >> driver for this PWM fan controller. > ... > >> +config PWM_INTEL_LGM >> + tristate "Intel LGM PWM support" >> + depends on OF && HAS_IOMEM >> + depends on X86 || COMPILE_TEST > For better test coverage you may rewrite this > > depends on HAS_IOMEM > depends on (OF && X86) || COMPILE_TEST Sure, will update. >> + select REGMAP_MMIO >> + help >> + Generic PWM fan controller driver for LGM SoC. >> + >> + To compile this driver as a module, choose M here: the module >> + will be called pwm-intel-lgm. > ... > >> +#include <linux/bitfield.h> >> +#include <linux/clk.h> >> +#include <linux/module.h> >> +#include <linux/of_device.h> > This should be mod_devicetable.h. Well noted. >> +#include <linux/pwm.h> >> +#include <linux/regmap.h> >> +#include <linux/reset.h> > ... > >> +#define LGM_PWM_PERIOD_2WIRE_NSECS 40000000 > NSECS -> NS > 40000000 -> (40 * NSEC_PER_MSEC) Well noted. > ... > >> + if (state->polarity != PWM_POLARITY_NORMAL || >> + state->period < pc->period) > It can be one line. Ok. >> + return -EINVAL; > ... > >> + if (!state->enabled) { >> + ret = lgm_pwm_enable(chip, 0); >> + return ret; > What is the point? I guess you mean to change it to return lgm_pwm_enable(chip, 0); Will do, thanks. >> + } > ... > >> + ret = lgm_pwm_enable(chip, 1); >> + >> + return ret; > Ditto. > > ... > >> + state->duty_cycle = DIV_ROUND_UP(duty * pc->period, >> + LGM_PWM_MAX_DUTY_CYCLE); > One line? Ok. > ... > >> + struct lgm_pwm_chip *pc; >> + struct device *dev = &pdev->dev; > Use reversed xmas tree order. Sure, will update. >> + void __iomem *io_base; >> + int ret; > ... > >> + pc->regmap = devm_regmap_init_mmio(dev, io_base, &lgm_pwm_regmap_config); >> + if (IS_ERR(pc->regmap)) { >> + ret = PTR_ERR(pc->regmap); >> + if (ret != -EPROBE_DEFER) >> + dev_err(dev, "failed to init register map: %pe\n", >> + pc->regmap); >> + return ret; > dev_err_probe() Will update. Thanks. >> + } > ... > >> + pc->clk = devm_clk_get(dev, NULL); >> + if (IS_ERR(pc->clk)) { >> + ret = PTR_ERR(pc->clk); >> + if (ret != -EPROBE_DEFER) >> + dev_err(dev, "failed to get clock: %pe\n", pc->clk); >> + return ret; > Ditto. > >> + } >> + >> + pc->rst = devm_reset_control_get_exclusive(dev, NULL); >> + if (IS_ERR(pc->rst)) { >> + ret = PTR_ERR(pc->rst); >> + if (ret != -EPROBE_DEFER) >> + dev_err(dev, "failed to get reset control: %pe\n", >> + pc->rst); >> + return ret; > Ditto. > >> + } >> + >> + ret = reset_control_deassert(pc->rst); >> + if (ret) { >> + if (ret != -EPROBE_DEFER) >> + dev_err(dev, "cannot deassert reset control: %pe\n", >> + ERR_PTR(ret)); >> + return ret; > Ditto. > >> + } > ... > >> + ret = clk_prepare_enable(pc->clk); > Wrap it with devm_add_action_or_reset(). Same for reset_control_deassert(). > You probably can even put them under one function. I did some study and research for using devm_add_action_or_reset(). But still i have some doubts. Below steps is what i intend to do in order to switch to using this API. Please do review and let me know it is ok and i am not missing anything else. Thanks. 1. Call reset_control_assert() 2. Call clk_prepare_enable() 3. Call pwmchip_add() 4. Call devm_add_action_or_reset(dev, my_action, pc) 5. Remove explicit calls to unprepare/reset_control_assert from probe in failure cases. 6. static void my_action(void *pc) { pwmchip_remove(&pc->chip); clk_disable_upprepare(pc->clk); reset_control_assert(pc->rst); } 7. Remove platform_driver.remove() entirely. >> + if (ret) { >> + dev_err(dev, "failed to enable clock\n"); >> + reset_control_assert(pc->rst); >> + return ret; >> + } > ... > >> + ret = pwmchip_add(&pc->chip); >> + if (ret < 0) { > Does ' < 0' have any meaning? I use < 0 because this API's return code is mentioned as below: Returns: 0 on success or a negative error code on failure. Also, all other PWM drivers check for <0 for this call. >> + dev_err(dev, "failed to add PWM chip: %pe\n", ERR_PTR(ret)); >> + clk_disable_unprepare(pc->clk); >> + reset_control_assert(pc->rst); >> + return ret; >> + } > ... > >> + ret = pwmchip_remove(&pc->chip); >> + if (ret < 0) > Ditto. Same as above. >> + return ret; Thanks. Regards, Rahul