Hi, On Mon, 6 Jun 2016 15:02:21 +0300 Tomi Valkeinen wrote: > Hi, > > On 06/06/16 13:44, Lothar Waßmann wrote: > > 'brightness' is usually an index into a table of duty_cycle values, > > where the value at index 0 may well be non-zero > > (tegra30-apalis-eval.dts and tegra30-colibri-eval-v3.dts are real-life > > examples). > > Thus brightness == 0 does not necessarily mean that the PWM output > > will be inactive. > > Check for 'duty_cycle == 0' rather than 'brightness == 0' to decide > > whether to disable the PWM. > > The binding doc does say: > > - brightness-levels: Array of distinct brightness levels. Typically these > are in the range from 0 to 255, but any range starting at 0 will do. > The actual brightness level (PWM duty cycle) will be interpolated > from these values. 0 means a 0% duty cycle (darkest/off), while the > last value in the array represents a 100% duty cycle (brightest). > So, what should I do, when I need a range of levels that doesn't start at 0? E.g. if the brightness is inverse proportional to the PWM duty cycle.
Lothar Waßmann
