Re: [PATCH v5 07/12] leds: leds-gpio: Add support for GPIO descriptors

[Rafael J. Wysocki]

On Tuesday, October 28, 2014 04:26:25 PM Linus Walleij wrote:
> On Fri, Oct 17, 2014 at 2:11 PM, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> 
> > From: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> >
> > GPIO descriptors are the preferred way over legacy GPIO numbers
> > nowadays. Convert the driver to use GPIO descriptors internally but
> > still allow passing legacy GPIO numbers from platform data to support
> > existing platforms.
> >
> > Signed-off-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> > Acked-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
> > Acked-by: Bryan Wu <cooloney@xxxxxxxxx>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> (...)
> 
> >         if (led_dat->blinking) {
> > -               led_dat->platform_gpio_blink_set(led_dat->gpio,
> > -                                                led_dat->new_level,
> > -                                                NULL, NULL);
> > +               int gpio = desc_to_gpio(led_dat->gpiod);
> > +               int level = led_dat->new_level;
> 
> So this desc_to_gpio() is done only to call the legacy callback below?
> 
> > +               if (gpiod_is_active_low(led_dat->gpiod))
> > +                       level = !level;
> 
> And that leads to making it necessary to have this helper variable
> to invert the level since that callback does not pass a descriptor
> (which would inherently know if it's active low)....
> 
> > +
> > +               led_dat->platform_gpio_blink_set(gpio, level, NULL, NULL);
> 
> Is it *really* impossible to change all the users of this callback?

You said it could be done in a followup patch.  Here:
http://marc.info/?l=linux-acpi&m=141154536921643&w=4

And Mika said he would add that to his TODO list:
http://marc.info/?l=linux-acpi&m=141155173924101&w=4

I suppose that is still valid.

> 
> >                 led_dat->blinking = 0;
> >         } else
> > -               gpio_set_value_cansleep(led_dat->gpio, led_dat->new_level);
> > +               gpiod_set_value_cansleep(led_dat->gpiod, led_dat->new_level);
> 
> (...)
> >         /* Setting GPIOs with I2C/etc requires a task context, and we don't
> >          * seem to have a reliable way to know if we're already in one; so
> >          * let's just assume the worst.
> > @@ -72,11 +73,16 @@ static void gpio_led_set(struct led_clas
> >                 schedule_work(&led_dat->work);
> >         } else {
> >                 if (led_dat->blinking) {
> > -                       led_dat->platform_gpio_blink_set(led_dat->gpio, level,
> > -                                                        NULL, NULL);
> > +                       int gpio = desc_to_gpio(led_dat->gpiod);
> > +
> > +                       if (gpiod_is_active_low(led_dat->gpiod))
> > +                               level = !level;
> > +
> > +                       led_dat->platform_gpio_blink_set(gpio, level, NULL,
> > +                                                        NULL);
> 
> Same comment.
> 
> > @@ -85,9 +91,10 @@ static int gpio_blink_set(struct led_cla
> >  {
> >         struct gpio_led_data *led_dat =
> >                 container_of(led_cdev, struct gpio_led_data, cdev);
> > +       int gpio = desc_to_gpio(led_dat->gpiod);
> >
> >         led_dat->blinking = 1;
> > -       return led_dat->platform_gpio_blink_set(led_dat->gpio, GPIO_LED_BLINK,
> > +       return led_dat->platform_gpio_blink_set(gpio, GPIO_LED_BLINK,
> >                                                 delay_on, delay_off);
> 
> Same comment.
> 
> > @@ -97,24 +104,33 @@ static int create_gpio_led(const struct
> >  {
> >         int ret, state;
> >
> > -       led_dat->gpio = -1;
> > +       if (!template->gpiod) {
> > +               unsigned long flags = 0;
> >
> > -       /* skip leds that aren't available */
> > -       if (!gpio_is_valid(template->gpio)) {
> > -               dev_info(parent, "Skipping unavailable LED gpio %d (%s)\n",
> > -                               template->gpio, template->name);
> > -               return 0;
> > +               /* skip leds that aren't available */
> > +               if (!gpio_is_valid(template->gpio)) {
> > +                       dev_info(parent, "Skipping unavailable LED gpio %d (%s)\n",
> > +                                       template->gpio, template->name);
> > +                       return 0;
> > +               }
> > +
> > +               if (template->active_low)
> > +                       flags |= GPIOF_ACTIVE_LOW;
> > +
> > +               ret = devm_gpio_request_one(parent, template->gpio, flags,
> > +                                           template->name);
> > +               if (ret < 0)
> > +                       return ret;
> > +
> > +               led_dat->gpiod = gpio_to_desc(template->gpio);
> > +               if (IS_ERR(led_dat->gpiod))
> > +                       return PTR_ERR(led_dat->gpiod);
> >         }
> 
> OK so this is the legacy codepath: point it out in a big fat
> comment that this is the legacy codepath.

That looks like it could be done in a followup patch too.

Since the series is in my linux-next branch at this point, I really wouldn't
like to reshuffle commits in it if that can be avoided.

> > Index: linux-pm/include/linux/leds.h
> > ===================================================================
> > --- linux-pm.orig/include/linux/leds.h
> > +++ linux-pm/include/linux/leds.h
> > @@ -251,6 +251,7 @@ struct gpio_led {
> >         unsigned        retain_state_suspended : 1;
> >         unsigned        default_state : 2;
> >         /* default_state should be one of LEDS_GPIO_DEFSTATE_(ON|OFF|KEEP) */
> > +       struct gpio_desc *gpiod;
> 
> Put the new struct member right below the current "gpio"
> member,

It was done like that in previous versions, but turned out to cause problems
to happen in testing.  Unfortunately, I don't seem to be able to find a pointer
to the original report ATM, but perhaps Mika can.  Mika?

> and add comments saying that either needs to be
> specified but "gpio" is deprecated for "gpiod".

Kind regards,
Rafael

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