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

Rafael J. Wysocki
2014-10-28T21:56:09Z

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@rjwysocki.net> wrote:
>
> > From: Mika Westerberg <mika.westerberg@linux.intel.com>
> >
> > 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@linux.intel.com>
> > Acked-by: Alexandre Courbot <acourbot@nvidia.com>
> > Acked-by: Bryan Wu <cooloney@gmail.com>
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> (...)
>
> > 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