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From: Greg KH <gregkh@linuxfoundation.org>
To: Pavel Machek <pavel@denx.de>
Cc: Jacek Anaszewski <jacek.anaszewski@gmail.com>,
	Dan Murphy <dmurphy@ti.com>,
	linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH v17 00/17] Multi Color LED Framework
Date: Thu, 27 Feb 2020 13:43:29 +0100
Message-ID: <20200227124329.GA994747@kroah.com> (raw)
In-Reply-To: <20200227105808.GA27003@duo.ucw.cz>

On Thu, Feb 27, 2020 at 11:58:08AM +0100, Pavel Machek wrote:
> Hi, Jacek!
> 
> (and thanks for doing this).
> 
> > We have here long lasting discussion related to LED multicolor class
> > sysfs interface design. We went through several iterations and worked
> > out the solution with individual file per each color sub-LED in the
> > color directory as shown below:
> > 
> > /sys/class/leds/<led>/colors/<color>_intensity
> > 
> > This is in line with one-value-per-file sysfs rule, that is being
> > frequently highlighted, and we even had not so long ago a patch
> > for led cpu trigger solving the problem caused by this rule not
> > being adhered to.
> 
> Yep. One of the problems is that it is nice to change all the hardware
> channels at once to produce color (it is often on i2c -- and slow), so
> current proposals use "interesting" kind of latching.
> 
> > Now we have the voice below bringing to attention another caveat
> > from sysfs documentation:
> > 
> > "it is socially acceptable to express an array of values of the same
> > type"
> > 
> > and proposing the interface in the form of two files:
> > 
> > channel_intensity (file containing array of u32's)
> > channel_names (usually containing "red green blue")
> 
> And thus I want to have it in one file, so it is naturaly atomic. RGB
> leds with 3 channels are common; I have not user yet, but there are
> RGBW with 4 channels (and some more exotic stuff). I don't expect to
> have more than 5 channels.

Writing 3 or 4 or 5 numbers all at once in a single sysfs file to
represent a single output should be fine.

thanks,

greg k-h

  reply index

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-27 15:00 Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 01/17] dt-bindings: leds: Add multicolor ID to the color ID list Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 02/17] " Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 03/17] leds: multicolor: Introduce a multicolor class definition Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 04/17] dt: bindings: lp50xx: Introduce the lp50xx family of RGB drivers Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 05/17] leds: lp50xx: Add the LP50XX family of the RGB LED driver Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 06/17] dt: bindings: lp55xx: Be consistent in the document with LED acronym Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 07/17] dt: bindings: lp55xx: Update binding for Multicolor Framework Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 08/17] ARM: dts: n900: Add reg property to the LP5523 channel node Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 09/17] ARM: dts: imx6dl-yapp4: Add reg property to the lp5562 " Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 10/17] ARM: dts: ste-href: Add reg property to the LP5521 channel nodes Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 11/17] leds: lp55xx: Convert LED class registration to devm_* Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 12/17] leds: lp55xx: Add multicolor framework support to lp55xx Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 13/17] leds: lp5523: Update the lp5523 code to add multicolor brightness function Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 14/17] leds: lp5521: Add multicolor framework multicolor brightness support Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 15/17] leds: lp55xx: Fix checkpatch file permissions issues Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 16/17] leds: lp5523: Fix checkpatch issues in the code Dan Murphy
2020-01-27 15:00 ` [RESEND PATCH v17 17/17] dt: bindings: Update lp55xx binding to recommended LED naming Dan Murphy
2020-02-12 13:09 ` [RESEND PATCH v17 00/17] Multi Color LED Framework Dan Murphy
2020-02-25 10:19   ` Pavel Machek
2020-02-25 22:17     ` Jacek Anaszewski
2020-02-25 22:44       ` Dan Murphy
2020-02-26 12:59       ` Pavel Machek
2020-02-26 20:45         ` Jacek Anaszewski
2020-02-26 22:10           ` Dan Murphy
2020-02-27 10:58           ` Pavel Machek
2020-02-27 12:43             ` Greg KH [this message]
2020-02-27 13:07               ` Dan Murphy
2020-02-27 13:29                 ` Dan Murphy
2020-02-27 21:22                 ` Jacek Anaszewski
2020-02-28  7:42                   ` Greg KH
2020-02-28  9:34                     ` Pavel Machek
2020-02-28 12:30                     ` Dan Murphy
2020-02-28  9:39                   ` Pavel Machek

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