From: Pavel Machek <pavel@ucw.cz>
To: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>,
Rob Herring <robh@kernel.org>, Richard Purdie <rpurdie@rpsys.net>,
linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org,
linux-arm-msm@vger.kernel.org,
Mark Rutland <mark.rutland@arm.com>,
devicetree@vger.kernel.org
Subject: Re: [PATCH 1/2] leds: Add driver for Qualcomm LPG
Date: Fri, 7 Apr 2017 14:54:40 +0200 [thread overview]
Message-ID: <20170407125440.GD4756@amd> (raw)
In-Reply-To: <bf999f34-4509-6f0b-602c-f82d50a18e97@gmail.com>
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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
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next prev parent reply other threads:[~2017-04-07 12:54 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-23 5:54 [PATCH 1/2] leds: Add driver for Qualcomm LPG Bjorn Andersson
2017-03-23 5:54 ` [PATCH 2/2] DT: leds: Add Qualcomm Light Pulse Generator binding Bjorn Andersson
2017-03-29 2:26 ` Rob Herring
2017-03-29 19:26 ` Bjorn Andersson
2017-03-29 22:13 ` Pavel Machek
2017-03-23 20:37 ` [PATCH 1/2] leds: Add driver for Qualcomm LPG Pavel Machek
2017-03-27 4:48 ` Bjorn Andersson
2017-03-29 2:17 ` Rob Herring
2017-03-29 19:07 ` Bjorn Andersson
2017-03-29 22:23 ` Pavel Machek
2017-03-30 0:09 ` Bjorn Andersson
2017-03-30 7:43 ` Pavel Machek
2017-03-31 9:28 ` Jacek Anaszewski
2017-04-02 12:54 ` Jacek Anaszewski
2017-04-03 18:21 ` Bjorn Andersson
2017-04-03 20:38 ` Jacek Anaszewski
2017-04-10 9:52 ` Pavel Machek
2017-04-03 19:00 ` Bjorn Andersson
2017-04-03 20:38 ` Jacek Anaszewski
2017-04-07 20:26 ` Bjorn Andersson
2017-04-08 9:57 ` Pavel Machek
2017-04-08 13:39 ` Pavel Machek
2017-04-09 12:32 ` Jacek Anaszewski
2017-04-10 19:19 ` Bjorn Andersson
2017-04-11 17:54 ` Pavel Machek
2017-04-11 23:17 ` Bjorn Andersson
2017-04-07 13:32 ` Pavel Machek
2017-04-07 20:36 ` Bjorn Andersson
2017-04-08 9:33 ` Pavel Machek
2017-04-07 12:54 ` Pavel Machek [this message]
2022-05-23 16:30 ` Pavel Machek
2022-05-23 22:01 ` Marijn Suijten
2022-05-23 22:18 ` Pavel Machek
2022-05-24 18:19 ` Marijn Suijten
2022-05-24 15:02 ` Bjorn Andersson
2022-05-24 18:26 ` Marijn Suijten
2022-05-24 20:10 ` Pavel Machek
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