On Sun, 16 Jul 2023, Marek Behún wrote: > On Sun, 16 Jul 2023 11:19:30 +0200 > Pavel Machek <pavel@xxxxxx> wrote: > > > Hi! > > > > > Using binary brightness makes more sense for this controller, because > > > internally in the MCU it works that way: the LED has a color, and a > > > state whether it is ON or OFF. > > > > So, controller can do (1, 3, 5) but not (3, 3, 3)? > > > > > The resulting brightness computation with led_mc_calc_color_components() > > > will now always result in either (0, 0, 0) or the multi_intensity value. > > > > Won't that limit you to 8 colors total? > > > > I guess I`m confused how this hw works... > > Hi Pavel. > > No no no. That's not how it is. > > The HW exposes color control for three channels (RGB), each channel with > range 0-255 (so 16M colors). The driver exposes this via the > multi_intensity sysfs file. This is communicated to the HW via > LED_SET_COLOR I2C command. > > HW also exposes setting the LED ON and OFF, via the LED_SET_STATE > I2C command. > > We currently have the following sysfs files via which we set LED state > and color: > brightness > multi_intensity > > Because currently the driver sets max_brightness to 255, the actual > color that is sent to HW is recalculated via > led_mc_calc_color_components(). For example with > > $ echo 255 255 100 >multi_intensity > $ echo 150 >brightness > > the led_mc_calc_color_components() function recalculates the channel > intensities with formula > brightness * channel_intensity / max_brightness > and so the (255, 255, 100) tuple is converted to (150, 150, 58) before > sending to HW. > > What I think would make more sense is to make the two sysfs files > brightness > multi_intensity > correspond 1-to-1 with I2C commands LED_SET_STATE and LED_SET_COLOR. > > This can be simply done by setting max_brightness to 1. The brightness > sysfs file then can simply control whether the LED is ON or OFF. The > multi_intensity file control the color. > > I realize now that in the patch I should also make away with the call > to led_mc_calc_color_components()... FYI, due to the revelations above, I'm dropping this from my queue. -- Lee Jones [李琼斯]
