From: Jacek Anaszewski <jacek.anaszewski@gmail.com>
To: Pavel Machek <pavel@ucw.cz>
Cc: Jacek Anaszewski <j.anaszewski@samsung.com>,
Heiner Kallweit <hkallweit1@gmail.com>, Greg KH <greg@kroah.com>,
linux-leds@vger.kernel.org,
Benjamin Tissoires <benjamin.tissoires@redhat.com>,
linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
pali.rohar@gmail.com, sre@kernel.org, khilman@kernel.org,
aaro.koskinen@iki.fi, ivo.g.dimitrov.75@gmail.com,
Patrik Bachan <patrikbachan@gmail.com>,
serge@hallyn.com
Subject: Re: [PATCH v5 1/4] leds: core: add generic support for RGB Color LED's
Date: Fri, 8 Apr 2016 20:47:28 +0200 [thread overview]
Message-ID: <5707FCC0.6000204@gmail.com> (raw)
In-Reply-To: <20160407204540.GA11202@amd>
On 04/07/2016 10:45 PM, Pavel Machek wrote:
> Hi!
>
>>>> The "color" attribute would contain "R G B" values. Setting the "color"
>>>> attribute of any of the three LED class devices would affect brightness
>>>> properties (i.e. constituent colors) of the remaining two ones.
>>>> It would result in disabling any active triggers and writing all the
>>>> three color settings to the RGB LED controller at one go.
>>>
>>> Having one attribute across three devices is rather ugly. And we'll
>>> need to solve the pattern issue one day.
>>>
>>> What's tricky about patterns is that you need to control 3 (or more)
>>> leds at a time. Problem you are trying to solve here is ... control of
>>> 3 leds, at the same time.
>>>
>>> So let's solve them together.
>>
>> OK, now I've got your point. So we'd need to have a means for defining
>> patterns. The interface could be located at /sys/class/leds/patterns.
>>
>> We'd need to have a flexible way for defining LED class devices involved
>> in a pattern. Since we cannot guarantee no space in a LED class device
>> name, then a single attribute containing space separated list is not an
>> option. We'd have to create a predefined set of attributes that would
>> contain LED class device name. Predefined implies that it would be
>> a fixed number, i.e. either some attributes would always remain unused
>> or, which is even worse, we could run out of free attributes for some
>> use cases.
>
> There's a better solution: make pattern behave as a trigger for leds
> it controls.
>
> So we'd have
>
> /sys/class/leds/patterns/lp5523
>
> then we'd have
>
> /sys/class/leds/lp5523::red/trigger = "lp5523:1"
> /sys/class/leds/lp5523::green/trigger = "lp5523:2"
> /sys/class/leds/lp5523::blue/trigger = "lp5523:3"
>
> (or something similar, I'd have to boot the n900 to see the exact
> names).
How about implementing patterns as a specific typer of triggers?
Let's say we have ledtrig-rgb-pattern:
After setting a trigger following sysfs attribute would appear
in a LED class device sysfs interface:
$cat /sys/class/lp5523::red/rgb_color
red green blue [none]
$echo "red" > /sys/class/leds/lp5523::red/rgb_color
and similarly
$echo "green" > /sys/class/leds/lp5523::green/rgb_color
$echo "blue" > /sys/class/leds/lp5523::blue/rgb_color
Similar approach could be applied for blink patterns:
There could be additional attributes provided for defining
the position in a blink sequence, or/and blink period.
Now it has become apparent to me that triggers in fact assure
LED class device synchronization.
> That means that we don't need space-separated lists. (And actually
> gives us more flexibility; Maemo for example used the pattern engine
> not for RGB led, but for 6 keyboard backlight leds.)
>
>> The same constraints would appear if we wanted to be able to define
>> more than one pattern.
>
> We'd like to have more than one pattern _engine_, but it should be
> enough to have one pattern per pattern engine at a time.
>
>> It would be best to work out more flexible solution. I wonder if
>> ioctl interface isn't the only option.
>
> Well, there's configs, which is more flexible, but...
>
> Best regards,
>
> Pavel
>
--
Best regards,
Jacek Anaszewski
next prev parent reply other threads:[~2016-04-08 18:48 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-01 21:26 [PATCH v5 1/4] leds: core: add generic support for RGB Color LED's Heiner Kallweit
2016-03-04 9:04 ` Jacek Anaszewski
2016-03-29 10:02 ` Pavel Machek
2016-03-29 20:38 ` Heiner Kallweit
2016-03-29 21:43 ` Pavel Machek
2016-03-29 22:03 ` Pavel Machek
2016-03-30 5:58 ` Heiner Kallweit
2016-04-01 12:52 ` Pavel Machek
2016-03-30 8:07 ` Jacek Anaszewski
2016-03-30 13:03 ` Pavel Machek
2016-03-30 13:59 ` Heiner Kallweit
2016-03-31 8:17 ` Jacek Anaszewski
2016-04-01 12:55 ` Pavel Machek
2016-04-01 13:28 ` Jacek Anaszewski
2016-04-01 14:07 ` Pavel Machek
2016-04-01 14:27 ` Jacek Anaszewski
2016-04-01 15:03 ` Pavel Machek
2016-04-01 12:53 ` Pavel Machek
2016-03-30 7:57 ` Jacek Anaszewski
2016-04-01 13:57 ` Pavel Machek
2016-04-01 18:56 ` Jacek Anaszewski
2016-04-01 21:18 ` Pavel Machek
2016-04-04 21:34 ` Jacek Anaszewski
2016-04-05 9:01 ` Pavel Machek
2016-04-05 19:45 ` Jacek Anaszewski
2016-04-05 20:43 ` Heiner Kallweit
2016-04-05 22:15 ` Jacek Anaszewski
2016-04-06 9:16 ` Pavel Machek
2016-04-06 9:12 ` Pavel Machek
2016-04-06 8:52 ` Pavel Machek
2016-04-06 9:53 ` Jacek Anaszewski
2016-04-07 20:45 ` Pavel Machek
2016-04-08 18:47 ` Jacek Anaszewski [this message]
2016-04-09 16:01 ` Pavel Machek
2016-04-12 7:13 ` Jacek Anaszewski
2016-04-15 11:53 ` Pavel Machek
2016-04-18 9:12 ` Jacek Anaszewski
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