Help wanted in LED subsystem

Help wanted in LED subsystem

[Pavel Machek]

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Hi!

In linux-next, I published TODO list for LED subsystem. Is that
something linux-kernel-mentees could help with?

Best regards,
							Pavel


+++ b/drivers/leds/TODO
@@ -0,0 +1,58 @@
+-*- org -*-
+
+* On/off LEDs should have max_brightness of 1
+* Get rid of enum led_brightness
+
+It is really an integer, as maximum is configurable. Get rid of it, or
+make it into typedef or something.
+
+* Review atomicity requirements in LED subsystem
+
+Calls that may and that may not block are mixed in same structure, and
+semantics is sometimes non-intuitive. (For example blink callback may
+not sleep.) Review the requirements for any bugs and document them
+clearly.
+
+* LED names are still a mess
+
+No two LEDs have same name, so the names are probably unusable for the
+userland. Nudge authors into creating common LED names for common
+functionality.
+
+? Perhaps check for known LED names during boot, and warn if there are
+LEDs not on the list?
+
+* Split drivers into subdirectories
+
+The number of drivers is getting big, and driver for on/off LED on a
+i/o port is really quite different from camera flash LED, which is
+really different from driver for RGB color LED that can run its own
+microcode. Split the drivers somehow.
+
+* Figure out what to do with RGB leds
+
+Multicolor is a bit too abstract. Yes, we can have
+Green-Magenta-Ultraviolet LED, but so far all the LEDs we support are
+RGB, and not even RGB-White or RGB-Yellow variants emerged.
+
+Multicolor is not a good fit for RGB LED. It does not really know
+about LED color.  In particular, there's no way to make LED "white".
+
+Userspace is interested in knowing "this LED can produce arbitrary
+color", which not all multicolor LEDs can.
+
+	Proposal: let's add "rgb" to led_colors in drivers/leds/led-core.c,
+	add corresponding device tree defines, and use that, instead of
+	multicolor for RGB LEDs.
+
+	We really need to do that now; "white" stuff can wait.
+
+RGB LEDs are quite common, and it would be good to be able to turn LED
+white and to turn it into any arbitrary color. It is essential that
+userspace is able to set arbitrary colors, and it might be good to
+have that ability from kernel, too... to allow full-color triggers.
+
+* Command line utility to manipulate the LEDs?
+
+/sys interface is not really suitable to use by hand, should we have
+an utility to perform LED control?

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [Linux-kernel-mentees] Help wanted in LED subsystem

[Shuah Khan]

Hi Pavel,

On 9/25/20 4:47 AM, Pavel Machek wrote:
> Hi!
> 
> In linux-next, I published TODO list for LED subsystem. Is that
> something linux-kernel-mentees could help with?
> 
> Best regards,
> 							Pavel
> 

Thanks for putting this list together. Will you be able to define
some time estimates for there items? We can definitely add these
as projects to get done.

I am working on mentorship project plan for next year and we also have
an active extended mentorship program underway since June and will
continue until June 2021.

Things to consider is scope of each of these items in the TODO list
and mentor availability.

thanks,
-- Shuah