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Groups > linux.kernel > #1210604
| From | Andrew Lunn <andrew@lunn.ch> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH/RFC v6 02/36] leds: Add led_set_brightness_sync to the public LED subsystem API |
| Date | 2015-08-20 18:00 +0200 |
| Message-ID | <pZApX-YM-11@gated-at.bofh.it> (permalink) |
| References | <pZzkd-7Tp-3@gated-at.bofh.it> <pZzke-7Tp-15@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, Aug 20, 2015 at 04:43:32PM +0200, Jacek Anaszewski wrote:
> led_set_brightness_sync function was visible only internally to the
> LED subsystem. It is now being made publicly available since it has
> become apparent that this is a caller who should decide whether
> brightness is to be set in a synchronous or an asynchronous way.
>
> The function is modified to use brightness_set_blocking or
> brightness_set op, depending on which of them is implemented, in case
> brightness_set_sync op wasn't been provided.
>
> Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>
> Cc: Andrew Lunn <andrew@lunn.ch>
> Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
> Cc: Pavel Machek <pavel@ucw.cz>
> Cc: Stas Sergeev <stsp@users.sourceforge.net>
> ---
> drivers/leds/led-core.c | 25 +++++++++++++++++++++++++
> drivers/leds/leds.h | 13 -------------
> include/linux/leds.h | 15 +++++++++++++++
> 3 files changed, 40 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
> index 549de7e..3f3b71d 100644
> --- a/drivers/leds/led-core.c
> +++ b/drivers/leds/led-core.c
> @@ -141,6 +141,31 @@ void led_set_brightness(struct led_classdev *led_cdev,
> }
> EXPORT_SYMBOL(led_set_brightness);
>
> +int led_set_brightness_sync(struct led_classdev *led_cdev,
> + enum led_brightness value)
> +{
> + int ret = 0;
> +
> + led_cdev->brightness = min(value, led_cdev->max_brightness);
> +
> + if (led_cdev->flags & LED_SUSPENDED)
> + return 0;
> +
> + if (led_cdev->brightness_set_sync)
> + ret = led_cdev->brightness_set_sync(led_cdev,
> + led_cdev->brightness);
> + else if (led_cdev->brightness_set_blocking)
> + led_cdev->brightness_set_blocking(led_cdev,
> + led_cdev->brightness);
> + else if (led_cdev->brightness_set)
> + led_cdev->brightness_set(led_cdev, led_cdev->brightness);
I don't see how this can be correct, when you say:
> +/**
> + * led_set_brightness_sync - set LED brightness synchronously
> + * @led_cdev: the LED to set
> + * @brightness: the brightness to set it to
> + *
> + * Set an LED's brightness immediately. This function will block
> + * the caller for the time required for accessing device register,
> + * and it can sleep.
led_cdev->brightness_set_sync() is fine, it is defined to the
synchronous.
led_cdev->brightness_set_blocking() is O.K.
But led_cdev->brightness_set() only guarantees:
/* Set LED brightness level */
/* Must not sleep, use a workqueue if needed */
void (*brightness_set)(struct led_classdev *led_cdev,
enum led_brightness brightness);
and it seems like 50% of the current drivers use work queues. It has
never been defined to by synchronous. If brightness_set() is your only
choice, you should return -ENOSUP.
With time, you could review all the drivers and move those that are
synchronous to brightness_set_sync().
Andrew
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[PATCH/RFC v6 00/36] Remove work queues from LED class drivers Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 31/36] leds: mc13783: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 14/36] leds: bd2802: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 07/36] Documentation: leds: Add description of brightness_set* ops Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 02/36] leds: Add led_set_brightness_sync to the public LED subsystem API Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
Re: [PATCH/RFC v6 02/36] leds: Add led_set_brightness_sync to the public LED subsystem API Andrew Lunn <andrew@lunn.ch> - 2015-08-20 18:00 +0200
[PATCH/RFC v6 27/36] leds: da9052: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 01/36] leds: Add brightness_set_blocking op Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
Re: [PATCH/RFC v6 01/36] leds: Add brightness_set_blocking op Andrew Lunn <andrew@lunn.ch> - 2015-08-20 17:30 +0200
Re: [PATCH/RFC v6 01/36] leds: Add brightness_set_blocking op Pavel Machek <pavel@ucw.cz> - 2015-08-24 13:50 +0200
[PATCH/RFC v6 17/36] leds: lm3642: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 06/36] leds: Drivers shouldn't enforce SYNC/ASYNC brightness setting Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 34/36] leds: gpio: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 09/36] leds: aat1290: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 03/36] leds: Improve asynchronous path of setting brightness Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 16/36] leds: lm3533: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 36/36] leds: lm355x: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 08/36] leds: ktd2692: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 33/36] leds: wm8350: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 18/36] leds: pca9532: Remove work queue for LEDs. Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 13/36] leds: adp5520: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 05/36] leds: Improve setting brightness in a non sleeping way Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
Re: [PATCH/RFC v6 05/36] leds: Improve setting brightness in a non sleeping way Andrew Lunn <andrew@lunn.ch> - 2015-08-20 18:20 +0200
Re: [PATCH/RFC v6 05/36] leds: Improve setting brightness in a non sleeping way Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-21 11:30 +0200
Re: [PATCH/RFC v6 05/36] leds: Improve setting brightness in a non sleeping way Andrew Lunn <andrew@lunn.ch> - 2015-08-21 20:00 +0200
Re: [PATCH/RFC v6 05/36] leds: Improve setting brightness in a non sleeping way Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2015-08-21 22:40 +0200
Re: [PATCH/RFC v6 05/36] leds: Improve setting brightness in a non sleeping way Andrew Lunn <andrew@lunn.ch> - 2015-08-21 22:50 +0200
Re: [PATCH/RFC v6 05/36] leds: Improve setting brightness in a non sleeping way Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-24 10:20 +0200
[PATCH/RFC v6 12/36] leds: 88pm860x: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 21/36] leds: lp8788: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 29/36] leds: lt3593: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 30/36] leds: max8997: Remove unneeded workqueue include Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 10/36] leds: max77693: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 15/36] leds: blinkm: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 22/36] leds: lp8860: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 11/36] leds: tlc591xx: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 32/36] leds: regulator: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
Re: [PATCH/RFC v6 32/36] leds: regulator: Remove work queue Antonio Ospite <ao2@ao2.it> - 2015-08-21 09:50 +0200
[PATCH/RFC v6 19/36] leds: lp3944: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
Re: [PATCH/RFC v6 19/36] leds: lp3944: Remove work queue Antonio Ospite <ao2@ao2.it> - 2015-08-21 09:50 +0200
[PATCH/RFC v6 20/36] leds: lp55xx: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 04/36] leds: Add an internal led_set_brightness_nosleep function Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 35/36] leds: pwm: remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 16:50 +0200
[PATCH/RFC v6 28/36] leds: dac124d085: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 17:00 +0200
[PATCH/RFC v6 25/36] leds: wm831x: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 17:00 +0200
[PATCH/RFC v6 26/36] leds: da903x: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 17:00 +0200
[PATCH/RFC v6 24/36] leds: pca963x: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 17:00 +0200
[PATCH/RFC v6 23/36] leds: pca955x: Remove work queue Jacek Anaszewski <j.anaszewski@samsung.com> - 2015-08-20 17:00 +0200
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