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Message-ID: <c65ca84d-8054-2244-1899-e4a9cb0842da@gmail.com>
Date: Wed, 30 Jan 2019 21:20:09 +0100
From: Jacek Anaszewski <jacek.anaszewski@...il.com>
To: Dan Murphy <dmurphy@...com>, robh+dt@...nel.org, pavel@....cz
Cc: linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org
Subject: Re: [RFC PATCH] leds: multicolor: Add sysfs interface definition
Dan,
On 1/30/19 8:59 PM, Dan Murphy wrote:
> Jacek
>
> On 1/30/19 1:37 PM, Jacek Anaszewski wrote:
>> Hi Dan,
>>
>> Thank you for the RFC.
>>
>> One vital thing is missing - documentation of brightness file must
>> be updated to define its semantics for LED multi color class.
>>
>> Either we need brightness-model file returning only "onoff" option
>> available, or, for time being, fix the max_brightness for LED multi
>> color class to 1 (which will map to max intensity level for each color).
>>
>
> I can make max_brightness default to 1 if not set by the LED driver.
>
> But the LP50xx has brightness controls so setting max_brightness from the driver should over ride
> the max of 1 in the upper level.
Yes, so the max_brightness should be updated basing on current
brightness-model. For LEDn_BRIGHTNESS of LP50xx we could have
"hw" or maybe even better just "lp50xx-linear" and "lp50xx-logarithmic"
- I just forgot about that capability of the device.
> For devices that do not support brightness as a separate control we can create a file called
> max_brightness_<color> that defines the max that a specific color can be set to. If max_brightness
> is set to 1 then create max_brightness_<color>. If max_brightness > 1 then do not create the files.
Right. We will need dedicated max_brightness for each color.
They should be placed also in the colors directory, next to the color
files.
> I don't think we have fully vetted the brightness-model yet so I prefer to omit
> it and possibly introduce that later.
We need to start from something. It will give better overview of the
whole idea.
Best regards,
Jacek Anaszewski
> Dan
>
>> Best regards,
>> Jacek Anaszewski
>>
>> On 1/30/19 7:30 PM, Dan Murphy wrote:
>>> Add a documentation of LED Multicolor LED class specific
>>> sysfs attributes.
>>>
>>> Signed-off-by: Dan Murphy <dmurphy@...com>
>>> ---
>>> .../ABI/testing/sysfs-class-led-multicolor | 38 +++++++++++++++++++
>>> 1 file changed, 38 insertions(+)
>>> create mode 100644 Documentation/ABI/testing/sysfs-class-led-multicolor
>>>
>>> diff --git a/Documentation/ABI/testing/sysfs-class-led-multicolor b/Documentation/ABI/testing/sysfs-class-led-multicolor
>>> new file mode 100644
>>> index 000000000000..19f8da9b150e
>>> --- /dev/null
>>> +++ b/Documentation/ABI/testing/sysfs-class-led-multicolor
>>> @@ -0,0 +1,38 @@
>>> +What: /sys/class/leds/<led>/color/sync_enable
>>> +Date: January 2019
>>> +KernelVersion: 5.0
>>> +Contact: Dan Murphy <dmurphy@...com>
>>> +Description: read/write
>>> + Writing a 1 to this file will enable the sychronization of all
>>> + the defined color LEDs within the LED node. Writing a 0 to
>>> + this file will disable syncing.
>>> +
>>> +What: /sys/class/leds/<led>/color/sync
>>> +Date: January 2019
>>> +KernelVersion: 5.0
>>> +Contact: Dan Murphy <dmurphy@...com>
>>> +Description: write only
>>> + Writing a 1 to this file while sync_enable is set to 1 will
>>> + synchronize all defined LEDs within the LED node. All LEDs
>>> + defined will be configured based on the brightness that has
>>> + been requested.
>>> +
>>> + If sync_enable is set to 0 then writing a 1 to sync has no
>>> + affect on the LEDs.
>>> +
>>> +What: /sys/class/leds/<led>/color/<led color>
>>> +Date: January 2019
>>> +KernelVersion: 5.0
>>> +Contact: Dan Murphy <dmurphy@...com>
>>> +Description: read/write
>>> + These files are dynamically created based on the colors defined
>>> + by the registrar of the class.
>>> + The led color(s) can be but not limited to red, green, blue,
>>> + white, amber and violet. If sync is enabled then writing the
>>> + brightness value of the LED is deferred until a 1 is
>>> + written to /sys/class/leds/<led>/color/sync. If syncing is
>>> + disabled then the LED brightness value will be written
>>> + immediately to the LED driver.
>>> +
>>> + The value of the color is from 0 to
>>> + /sys/class/leds/<led>/max_brightness.
>>>
>>
>
>
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