Hi! > Some criticism to this approach to HW triggers: > - every hw trigger for each LED has to be registered via current trigger > API. This will grow code size and memory footprint once this API is > widely used > - one HW trigger can only master one LED device (via private_led > member). So if I have, for example an ethernet switch with 8 ports, > and each port has 2 LEDs, and each LED has 10 possible HW triggering > mechanisms, with your proposed API one would need to register 8*2*10 > = 160 triggers Well, code is simple, and so far I have seen 2 HW triggering mechanisms, not 10. Maybe we should have a function to regiter a hw trigger for a LED, so that internal implementation can be changed more easily. Ondrej: You already have code using this, right? Can we get an example? > I too have been thinking about an API for HW LED triggers, and I > tinkered with it a little. Some time ago I sent some emails, with > subjects: > "RFC: LED hw triggering API" > "about my trigger-sources work" Perhaps it is time to send them one more time, so Ondrej can say if it works for him/looks okay for him? > My current thoughts about how HW LED triggers could work nicely is as > such: > - these members (maybe with different names) shall be added to struct > led_classdev: > available_hw_triggers() > - shall return a NULL terminated list of HW trigger names > available for this LED > set_hw_trigger() > - sets HW trigger for this LED. The LED triggering API shall > call this method after previous LED trigger is unset. If > called with NULL parameter, unsets HW trigger > current_hw_trigger > - name of the currently set HW LED trigger for this LED > - the driver registering the LED cdev informs abouth the LED being > capable of HW triggering - members available_hw_triggers and > set_hw_trigger must be set > - SW LED trigger and HW LED trigger are mutualy exclusive on one LED > - the trigger file in sysfs (/sys/class/leds/LED/trigger) shall first > list the available SW triggers, and then available hw triggers for > this LED, prefixed with "hw:" > When written, if the written trigger name starts with "hw:", > instead of setting SW trigger, a HW trigger is set via > set_hw_trigger() method This does not sound bad, either. Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
Attachment:
signature.asc
Description: Digital signature
