On 1/28/22 9:36 PM, Marek Behún wrote:
On Thu, 27 Jan 2022 22:24:21 +0100
Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx> wrote:
Hi Sven,
On 1/26/22 11:48 AM, sven@xxxxxxxxxxxxxxxx wrote:
From: Sven Schwermer <sven.schwermer@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
This allows to group multiple PWM-connected monochrome LEDs into
multicolor LEDs, e.g. RGB LEDs.
Signed-off-by: Sven Schwermer <sven.schwermer@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
---
[...]
+
+additionalProperties: false
+
+examples:
+ - |
+ #include <dt-bindings/leds/common.h>
+
+ rgb-led {
+ compatible = "pwm-leds-multicolor";
+
+ multi-led {
+ color = <LED_COLOR_ID_RGB>;
+ function = LED_FUNCTION_INDICATOR;
+ max-brightness = <65535>;
It doesn't make much sense to have such a big resolution of global
multi color brightness. 255 will be sufficient.
If the PWM supports it, why not?
On Omnia the default is 255, and since it is PWM, the change from 0/255
to 1/255 is much bigger then from, say, 15/255 to 16/255. So if 1/255
is too bright, you are then unable to set it less bright. I think 1024
or ever 65535 makes sense with PWMs.
With values other than 255 we will not achieve 24-bit RGB, which is one
problem, and the other one is non-linear brightness that can be achieved
with PWM. So probably we would need to add an additional note in the
documentation [0], saying that changing global brightness allows to
preserve combined LED hue only when all sub-leds are linear, and that it
will not be the case for PWM LEDs.
And I propose to change multi-led 'color' DT property value from
LED_COLOR_ID_RGB to LED_COLOR_ID_MULTI to avoid the impression that it
will work as traditional 24-bit RGB.
[0] Documentation/leds/leds-class-multicolor.rst
--
Best regards,
Jacek Anaszewski
