Geert Uytterhoeven <ge...@linux-m68k.org> writes: > Hi Pavel, > > On Sun, Mar 8, 2015 at 9:57 PM, Pavel Machek <pa...@ucw.cz> wrote: >> Ok, so I played with RGB LED a bit, and we have quite a gap in >> documentation: what 50% brightness means is non-trivial and very >> important in case we want to do smooth blinking and color transitions. >> >> Signed-off-by: Pavel Machek <pa...@ucw.cz> >> >> diff --git a/Documentation/ABI/testing/sysfs-class-led >> b/Documentation/ABI/testing/sysfs-class-led >> index 3646ec8..649d7a6 100644 >> --- a/Documentation/ABI/testing/sysfs-class-led >> +++ b/Documentation/ABI/testing/sysfs-class-led >> @@ -8,6 +8,11 @@ Description: >> non-zero brightness settings. The value is between 0 and >> /sys/class/leds/<led>/max_brightness. >> >> + If LED supports continuous brightness settings, 50% >> brightness >> + should correspond to 50% brightness perceived by human, in a >> similar >> + manner pixel brightness on monitor does (not 50% PWM). > > How many drivers do it right? How many don't? > > For those that don't, perhaps we handle the conversion between perceived and > pwm in the core, e.g. by adding a new flag to led_classdev.flags to indicate > the need for conversion?
Some LED controllers do the right thing in hardware, so any adjustment done in the core needs to be optional. -- Måns Rullgård m...@mansr.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
