Messages in this thread |  | | Subject | Re: [PATCH] leds: Allow drivers to update the core, and generate events on changes | From | Jacek Anaszewski <> | Date | Tue, 27 Dec 2016 23:57:26 +0100 |
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Hi Gabriele, Pavel,
On 12/27/2016 09:07 PM, Pavel Machek wrote: > Hi! > >> Similarily to commit 325253a6b2de ("backlight: Allow drivers to update >> the core, and generate events on changes"), inform userspace about >> brightness changes and allow drivers to request updates of the >> brightness value. > > First... we had similar patch in tree, and it caused problems, we are > now trying to figure out how to do it properly. > > LED can be updated many times per second, uevent is probably _not_ > good mechanism to achieve that. > > Generating uevent for /sys changes does not make much sense, right? > >> +extern void led_brightness_force_update(struct led_classdev *led_cdev, >> + enum led_brightness_update_reason reason); > > I see this may make some sense, but there are no uses for this in this > patch. > > My preffered solution would be ... for hardware that changes led > brightness itself, introduce a "trigger", so that userspace knows this > led is special, and then provide poll()able /sys fs file interested > parties can read.
I've recently submitted for a discussion the idea of "persistent triggers" [0]. Any feedback is very much appreciated.
[0] https://www.spinics.net/lists/linux-leds/msg07332.html
-- Best regards, Jacek Anaszewski
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