From: Pavel Machek <pavel@ucw.cz>
To: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Dan Murphy <dmurphy@ti.com>,
robh+dt@kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org
Subject: Re: [PATCH 2/2] leds: lp5024: Add the LP5024/18 RGB LED driver
Date: Sun, 30 Dec 2018 18:35:05 +0100 [thread overview]
Message-ID: <20181230173505.GA19593@amd> (raw)
In-Reply-To: <4b5a89ed-0c0b-3103-ca57-a0f97aa5ace9@gmail.com>
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On Sun 2018-12-30 18:09:35, Jacek Anaszewski wrote:
> On 12/29/18 8:07 PM, Pavel Machek wrote:
> >Hi!
> >
> >>>>With the "color" sysfs file it will make more sense to allow for user
> >>>>defined color palettes.
> >>>>
> >>>
> >>>I think defining these values in the device tree or acpi severely limits the devices
> >>>capabilities. Especially in development phases. If the knobs were exposed then the user space
> >>>can create new experiences. The color definition should be an absolute color defined in the dt and
> >>>either the framework or user space needs to mix these appropriately. IMO user space should set the policy
> >>>of the user experience and the dt/acpi needs to set the capabilities.
> >>>
> >>>I do like Pavels idea on defining the more standard binding pattern to "group" leds into a single group.
> >>>
> >>>Maybe the framework could take these groups and combine/group them into a single node with the groups colors.
> >>
> >>There is still HSV approach [0] in store. One problem with proposed
> >>implementation is fixed algorithm of RGB <-> HSV color space conversion.
> >>Maybe allowing for some board specific adjustments in DT would add
> >>more flexibility.
> >>
> >>[0] https://lkml.org/lkml/2017/8/31/255
> >
> >Yes we could do HSV. Problem is that that we do not really have RGB
> >available. We do have integers for red, green and blue, but they do
> >not correspond to RGB colorspace.
>
> OK, so conversion from HSV to RGB would only increase the aberration.
> So, let's stick to RGB - we've got to have some stable ground and this
> is something that the hardware at least pretends to be compliant
>with.
I'm not saying that we should stick to RGB. I'm just saying that
problem is complex.
And no, hardware does not even pretend to be compliant with RGB color
model ( https://en.wikipedia.org/wiki/RGB_color_model ). In
particular, in RGB there is non-linear brightness curve.
> Our problem is how to set the color atomically. With HSV approach we
> were to obviate the problem by mapping brightness file to the "V"
> component of that color space, and write all H,S and V values to the
> hardware only on write to brightness file.
I'm not sure how realistic the "atomic color" problem is. Computers
are way faster than human vision.
I believe problem to start with is the "white" problem. Setting
R=G=B=255 will _not_ result in anything close to white light on
hardware I have.
Anyway,
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:[~2018-12-30 17:35 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-19 16:26 [PATCH 0/2] LP5024/18 LED introduction Dan Murphy
2018-12-19 16:26 ` [PATCH 1/2] dt: bindings: lp5024: Introduce the lp5024 and lp5018 RGB driver Dan Murphy
2018-12-28 23:53 ` Rob Herring
2018-12-31 18:54 ` Dan Murphy
2019-01-08 20:33 ` Jacek Anaszewski
2019-01-08 20:53 ` Dan Murphy
2019-01-08 21:16 ` Jacek Anaszewski
2019-01-08 21:22 ` Dan Murphy
2019-01-09 20:12 ` Jacek Anaszewski
2019-01-09 21:12 ` Dan Murphy
2019-01-09 21:28 ` Jacek Anaszewski
2019-01-09 21:31 ` Dan Murphy
2019-01-10 18:44 ` Jacek Anaszewski
2019-01-10 19:22 ` Dan Murphy
2019-01-10 19:57 ` Jacek Anaszewski
2019-01-10 20:43 ` Dan Murphy
2019-01-10 22:03 ` Jacek Anaszewski
2019-01-10 23:51 ` Dan Murphy
2019-01-11 12:38 ` Dan Murphy
2019-01-11 21:52 ` Jacek Anaszewski
2019-01-12 17:09 ` Dan Murphy
2019-01-12 19:48 ` Jacek Anaszewski
2019-01-14 12:27 ` Dan Murphy
2019-01-14 20:11 ` Jacek Anaszewski
2019-01-14 20:14 ` Dan Murphy
2019-01-14 20:28 ` Jacek Anaszewski
2019-01-14 20:29 ` Dan Murphy
2018-12-19 16:26 ` [PATCH 2/2] leds: lp5024: Add the LP5024/18 RGB LED driver Dan Murphy
2018-12-19 19:04 ` Dan Murphy
2018-12-19 19:34 ` Pavel Machek
2018-12-19 19:41 ` Dan Murphy
2018-12-19 20:10 ` Pavel Machek
2018-12-19 20:41 ` Dan Murphy
2018-12-19 21:36 ` Jacek Anaszewski
2018-12-19 21:50 ` Dan Murphy
2018-12-20 12:40 ` Vesa Jääskeläinen
2018-12-20 13:56 ` Dan Murphy
2019-01-01 13:45 ` Vesa Jääskeläinen
2019-01-03 22:05 ` Jacek Anaszewski
2019-01-03 23:19 ` Vesa Jääskeläinen
2019-01-03 23:34 ` Pavel Machek
2019-01-04 19:49 ` Vesa Jääskeläinen
2019-01-04 20:43 ` Pavel Machek
2019-01-04 19:12 ` Jacek Anaszewski
2019-01-04 20:12 ` Pavel Machek
2019-01-04 21:37 ` Jacek Anaszewski
2019-01-04 22:07 ` Pavel Machek
2019-01-05 12:16 ` Jacek Anaszewski
2019-01-05 12:31 ` Pavel Machek
2019-01-05 13:16 ` Jacek Anaszewski
2019-01-05 22:12 ` Generic RGB LED support was " Pavel Machek
2019-01-06 15:52 ` Jacek Anaszewski
2019-01-07 19:13 ` Jacek Anaszewski
2019-01-07 19:36 ` Dan Murphy
2019-01-07 20:59 ` Jacek Anaszewski
2019-01-07 21:14 ` Dan Murphy
2019-01-08 21:18 ` Jacek Anaszewski
2019-01-08 21:25 ` Dan Murphy
2019-01-10 12:46 ` Dan Murphy
2019-01-10 19:23 ` Jacek Anaszewski
2019-01-10 19:58 ` Dan Murphy
2019-01-10 21:02 ` Jacek Anaszewski
2019-01-10 21:07 ` Dan Murphy
2019-01-08 22:59 ` Pavel Machek
2019-01-09 7:11 ` Vesa Jääskeläinen
2019-01-13 16:37 ` Jacek Anaszewski
2019-01-05 0:39 ` Vesa Jääskeläinen
2019-01-07 19:34 ` Dan Murphy
2019-01-09 6:20 ` Vesa Jääskeläinen
2019-01-07 21:13 ` Jacek Anaszewski
2019-01-07 21:15 ` Dan Murphy
2019-01-09 6:46 ` Vesa Jääskeläinen
2019-01-13 16:36 ` Jacek Anaszewski
2018-12-20 20:31 ` Jacek Anaszewski
2018-12-21 7:32 ` Jacek Anaszewski
2018-12-21 13:05 ` Dan Murphy
2018-12-29 18:28 ` Jacek Anaszewski
2018-12-29 19:07 ` Pavel Machek
2018-12-30 17:09 ` Jacek Anaszewski
2018-12-30 17:35 ` Pavel Machek [this message]
2018-12-31 15:43 ` Jacek Anaszewski
2018-12-31 15:47 ` Jacek Anaszewski
2018-12-31 19:15 ` Dan Murphy
2019-01-01 14:42 ` Jacek Anaszewski
2019-01-01 18:11 ` Dan Murphy
2019-01-01 22:06 ` Jacek Anaszewski
2018-12-31 16:28 ` Pavel Machek
2019-01-01 14:26 ` Jacek Anaszewski
2018-12-19 22:03 ` Pavel Machek
2018-12-19 22:08 ` Dan Murphy
2018-12-19 22:27 ` Pavel Machek
2018-12-20 1:31 ` Dan Murphy
2018-12-20 9:06 ` Pavel Machek
2018-12-20 14:03 ` Dan Murphy
2019-01-08 21:10 ` Jacek Anaszewski
2019-01-08 21:17 ` Dan Murphy
2019-07-22 20:59 ` Backlight in motorola Droid 4 Pavel Machek
2019-07-23 15:53 ` Dan Murphy
2019-07-24 8:22 ` Pavel Machek
2019-07-24 12:45 ` Pavel Machek
2019-07-24 15:10 ` Dan Murphy
2019-07-24 15:22 ` Dan Murphy
2019-07-26 14:38 ` Dan Murphy
2019-07-29 22:00 ` Pavel Machek
2019-07-30 18:21 ` Dan Murphy
2019-07-30 21:52 ` Pavel Machek
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