Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG

From	Pavel Machek <pavel@ucw.cz>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG
Date	2017-04-07 15:00 +0200
Message-ID	<ttBEC-7cJ-29@gated-at.bofh.it> (permalink)
References	(3 earlier) <tqr8K-2QS-17@gated-at.bofh.it> <tqugi-54n-17@gated-at.bofh.it> <tqvYK-6kg-19@gated-at.bofh.it> <tqD0e-2Ug-13@gated-at.bofh.it> <tr12y-2JJ-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

[Multipart message — attachments visible in raw view] - view raw

Hi!

> > Second, there are more issues than just patterns with the RGB
> > LED. Most important is ability to set particular colors. You want to
> > set the RGB LED to "white", but that does not mean you can set
> > red=green=blue=1.0. You want color to look the same on LCD and on the
> > LED, which means coefficients for white and some kind of function for
> > brightness-to-PWM conversion.
> 
> Shouldn't we leave that entirely to the userspace? Can we come up
> with coefficients that will guarantee the same result on all existing
> LCD devices?

I don't think we should. We want (red = 70%, green = 80%, blue = 20%)
to look approximately the same on all the hardware. That's currently
not the case; even (red = green = blue = 100%) is not white.

I believe easiest solution is "the kernel does the work", as it does
for LCD screens.

[Now... as long as userspace has enough information to display white
and specific colors, I don't care much -- having kernel present
coefficients for userspace would work, too.]

								Pavel

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

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Rob Herring <robh@kernel.org> - 2017-03-29 04:20 +0200
  Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Bjorn Andersson <bjorn.andersson@linaro.org> - 2017-03-29 21:10 +0200
    Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Pavel Machek <pavel@ucw.cz> - 2017-03-30 00:30 +0200
      Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Bjorn Andersson <bjorn.andersson@linaro.org> - 2017-03-30 02:20 +0200
        Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Pavel Machek <pavel@ucw.cz> - 2017-03-30 09:50 +0200
          Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2017-03-31 11:30 +0200
            Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2017-04-02 15:00 +0200
              Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Bjorn Andersson <bjorn.andersson@linaro.org> - 2017-04-03 20:30 +0200
                Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2017-04-03 22:40 +0200
                Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Pavel Machek <pavel@ucw.cz> - 2017-04-10 12:00 +0200
            Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Bjorn Andersson <bjorn.andersson@linaro.org> - 2017-04-03 21:10 +0200
              Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2017-04-03 22:40 +0200
                Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Bjorn Andersson <bjorn.andersson@linaro.org> - 2017-04-07 22:30 +0200
                Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Pavel Machek <pavel@ucw.cz> - 2017-04-08 12:00 +0200
                Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Pavel Machek <pavel@ucw.cz> - 2017-04-08 15:40 +0200
                Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2017-04-09 14:40 +0200
              Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Pavel Machek <pavel@ucw.cz> - 2017-04-07 15:40 +0200
                Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Bjorn Andersson <bjorn.andersson@linaro.org> - 2017-04-07 22:40 +0200
                Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Pavel Machek <pavel@ucw.cz> - 2017-04-08 11:40 +0200
            Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG Pavel Machek <pavel@ucw.cz> - 2017-04-07 15:00 +0200

csiph-web