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    SubjectRe: [PATCH v5 07/12] leds: leds-gpio: Add support for GPIO descriptors
    On Tue, Oct 28, 2014 at 10:56:09PM +0100, Rafael J. Wysocki wrote:
    > 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.

    Yes, I'll just let dust to settle before sending out a patch that
    converts the existing users of platform_gpio_blink_set() callback to
    gpio descriptors.

    >
    > >
    > > > 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?

    It is burried inside this thread:

    http://www.spinics.net/lists/arm-kernel/msg369522.html


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