diff options
Diffstat (limited to 'Documentation/pwm.txt')
| -rw-r--r-- | Documentation/pwm.txt | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/Documentation/pwm.txt b/Documentation/pwm.txt index 93cb97974986..ca895fd211e4 100644 --- a/Documentation/pwm.txt +++ b/Documentation/pwm.txt @@ -19,7 +19,8 @@ should instead register a static mapping that can be used to match PWM consumers to providers, as given in the following example: static struct pwm_lookup board_pwm_lookup[] = { - PWM_LOOKUP("tegra-pwm", 0, "pwm-backlight", NULL), + PWM_LOOKUP("tegra-pwm", 0, "pwm-backlight", NULL, + 50000, PWM_POLARITY_NORMAL), }; static void __init board_init(void) @@ -97,6 +98,13 @@ pwm_chip as argument which provides a description of the PWM chip, the number of PWM devices provided by the chip and the chip-specific implementation of the supported PWM operations to the framework. +When implementing polarity support in a PWM driver, make sure to respect the +signal conventions in the PWM framework. By definition, normal polarity +characterizes a signal starts high for the duration of the duty cycle and +goes low for the remainder of the period. Conversely, a signal with inversed +polarity starts low for the duration of the duty cycle and goes high for the +remainder of the period. + Locking ------- |