RE: [PATCH V2 1/2] hwmon: pwm-fan: Add profile support and add remove module support

[Sandipan Patra]

Hi Guenter,

Agreed with the suggestion with regards to fan profile support.
Looked at thermal driver and further planning to implement required changes in thermal core instead of pwm-fan driver.
Dropping the current series. 


Thanks & Regards,
Sandipan

> -----Original Message-----
> From: Guenter Roeck <groeck7@xxxxxxxxx> On Behalf Of Guenter Roeck
> Sent: Tuesday, June 2, 2020 7:58 PM
> To: Sandipan Patra <spatra@xxxxxxxxxx>
> Cc: Thierry Reding <treding@xxxxxxxxxx>; Jonathan Hunter
> <jonathanh@xxxxxxxxxx>; kamil@xxxxxxxxx; jdelvare@xxxxxxxx;
> robh+dt@xxxxxxxxxx; u.kleine-koenig@xxxxxxxxxxxxxx; Bibek Basu
> <bbasu@xxxxxxxxxx>; Bitan Biswas <bbiswas@xxxxxxxxxx>; Krishna Yarlagadda
> <kyarlagadda@xxxxxxxxxx>; linux-pwm@xxxxxxxxxxxxxxx; linux-
> hwmon@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-
> tegra@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH V2 1/2] hwmon: pwm-fan: Add profile support and add
> remove module support
> 
> External email: Use caution opening links or attachments
> 
> 
> On Mon, Jun 01, 2020 at 11:49:13AM +0530, Sandipan Patra wrote:
> > Add support for profiles mode settings.
> > This allows different fan settings for trip point temp/hyst/pwm.
> > Tegra194 has multiple fan-profiles support.
> >
> > Signed-off-by: Sandipan Patra <spatra@xxxxxxxxxx>
> 
> The subject says "remove module support". What is this supposed to be about ?
> 
> The code adds support for multiple cooling "profiles" but, unless I am really
> missing something, no means to actually select a profile.
> This adds a lot of complexity to the code with zero value.
> 
> Either case, and I may have mentioned this before, functionality like this should
> really reside in the thermal core and not in individual drivers.
> 
> > ---
> >
> > PATCH V2:
> >       Cleaned pwm_fan_remove support as it is not required.
> >
> >  drivers/hwmon/pwm-fan.c | 92
> > ++++++++++++++++++++++++++++++++++++++++++-------
> >  1 file changed, 80 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c index
> > 30b7b3e..1d2a416 100644
> > --- a/drivers/hwmon/pwm-fan.c
> > +++ b/drivers/hwmon/pwm-fan.c
> > @@ -3,8 +3,10 @@
> >   * pwm-fan.c - Hwmon driver for fans connected to PWM lines.
> >   *
> >   * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> > + * Copyright (c) 2020, NVIDIA Corporation.
> >   *
> >   * Author: Kamil Debski <k.debski@xxxxxxxxxxx>
> > + * Author: Sandipan Patra <spatra@xxxxxxxxxx>
> 
> You can not claim authorship for a driver by adding a few lines of code to it.
> 
> >   */
> >
> >  #include <linux/hwmon.h>
> > @@ -21,6 +23,8 @@
> >  #include <linux/timer.h>
> >
> >  #define MAX_PWM 255
> > +/* Based on OF max device tree node name length */
> > +#define MAX_PROFILE_NAME_LENGTH      31
> >
> >  struct pwm_fan_ctx {
> >       struct mutex lock;
> > @@ -38,6 +42,12 @@ struct pwm_fan_ctx {
> >       unsigned int pwm_fan_state;
> >       unsigned int pwm_fan_max_state;
> >       unsigned int *pwm_fan_cooling_levels;
> > +
> > +     unsigned int pwm_fan_profiles;
> > +     const char **fan_profile_names;
> > +     unsigned int **fan_profile_cooling_levels;
> > +     unsigned int fan_current_profile;
> > +
> >       struct thermal_cooling_device *cdev;  };
> >
> > @@ -227,28 +237,86 @@ static int pwm_fan_of_get_cooling_data(struct
> device *dev,
> >                                      struct pwm_fan_ctx *ctx)  {
> >       struct device_node *np = dev->of_node;
> > +     struct device_node *base_profile = NULL;
> > +     struct device_node *profile_np = NULL;
> > +     const char *default_profile = NULL;
> >       int num, i, ret;
> >
> > -     if (!of_find_property(np, "cooling-levels", NULL))
> > -             return 0;
> > +     num = of_property_count_u32_elems(np, "cooling-levels");
> > +     if (num <= 0) {
> > +             base_profile = of_get_child_by_name(np, "profiles");
> 
> You can not just add new properties like this without documenting it and getting
> approval by devicetree maintainers.
> 
> Guenter
> 
> > +             if (!base_profile) {
> > +                     dev_err(dev, "Wrong Data\n");
> > +                     return -EINVAL;
> > +             }
> > +     }
> > +
> > +     if (base_profile) {
> > +             ctx->pwm_fan_profiles =
> > +                     of_get_available_child_count(base_profile);
> >
> > -     ret = of_property_count_u32_elems(np, "cooling-levels");
> > -     if (ret <= 0) {
> > -             dev_err(dev, "Wrong data!\n");
> > -             return ret ? : -EINVAL;
> > +             if (ctx->pwm_fan_profiles <= 0) {
> > +                     dev_err(dev, "Profiles used but not defined\n");
> > +                     return -EINVAL;
> > +             }
> > +
> > +             ctx->fan_profile_names = devm_kzalloc(dev,
> > +                     sizeof(const char *) * ctx->pwm_fan_profiles,
> > +                                                     GFP_KERNEL);
> > +             ctx->fan_profile_cooling_levels = devm_kzalloc(dev,
> > +                     sizeof(int *) * ctx->pwm_fan_profiles,
> > +                                                     GFP_KERNEL);
> > +
> > +             if (!ctx->fan_profile_names
> > +                             || !ctx->fan_profile_cooling_levels)
> > +                     return -ENOMEM;
> > +
> > +             ctx->fan_current_profile = 0;
> > +             i = 0;
> > +             for_each_available_child_of_node(base_profile, profile_np) {
> > +                     num = of_property_count_u32_elems(profile_np,
> > +                                                     "cooling-levels");
> > +                     if (num <= 0) {
> > +                             dev_err(dev, "No data in cooling-levels inside profile
> node!\n");
> > +                             return -EINVAL;
> > +                     }
> > +
> > +                     of_property_read_string(profile_np, "name",
> > +                                             &ctx->fan_profile_names[i]);
> > +                     if (default_profile &&
> > +                             !strncmp(default_profile,
> > +                             ctx->fan_profile_names[i],
> > +                             MAX_PROFILE_NAME_LENGTH))
> > +                             ctx->fan_current_profile = i;
> > +
> > +                     ctx->fan_profile_cooling_levels[i] =
> > +                             devm_kzalloc(dev, sizeof(int) * num,
> > +                                                     GFP_KERNEL);
> > +                     if (!ctx->fan_profile_cooling_levels[i])
> > +                             return -ENOMEM;
> > +
> > +                     of_property_read_u32_array(profile_np, "cooling-levels",
> > +                             ctx->fan_profile_cooling_levels[i], num);
> > +                     i++;
> > +             }
> >       }
> >
> > -     num = ret;
> >       ctx->pwm_fan_cooling_levels = devm_kcalloc(dev, num, sizeof(u32),
> >                                                  GFP_KERNEL);
> >       if (!ctx->pwm_fan_cooling_levels)
> >               return -ENOMEM;
> >
> > -     ret = of_property_read_u32_array(np, "cooling-levels",
> > -                                      ctx->pwm_fan_cooling_levels, num);
> > -     if (ret) {
> > -             dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
> > -             return ret;
> > +     if (base_profile) {
> > +             memcpy(ctx->pwm_fan_cooling_levels,
> > +               ctx->fan_profile_cooling_levels[ctx->fan_current_profile],
> > +                                             num);
> > +     } else {
> > +             ret = of_property_read_u32_array(np, "cooling-levels",
> > +                             ctx->pwm_fan_cooling_levels, num);
> > +             if (ret) {
> > +                     dev_err(dev, "Property 'cooling-levels' cannot be read!\n");
> > +                     return -EINVAL;
> > +             }
> >       }
> >
> >       for (i = 0; i < num; i++) {