According to the circuit diagram of User LEDs - RGB described in the manual hifive-unleashed-a00.pdf[0] and hifive-unmatched-schematics-v3.pdf[1]. The behavior of PWM is acitve-high. According to the descriptionof PWM for pwmcmp in SiFive FU740-C000 Manual[2]. The pwm algorithm is (PW) pulse active time = (D) duty * (T) period. The `frac` variable is pulse "inactive" time so we need to invert it. So this patchset removes active-low in DTS and adds reverse logic to the driver. Updated patches: 2 New patches: (none) Unchanged patches: 1 Links: - [0]: https://sifive.cdn.prismic.io/sifive/c52a8e32-05ce-4aaf-95c8-7bf8453f8698_hifive-unleashed-a00-schematics-1.pdf - [1]: https://sifive.cdn.prismic.io/sifive/6a06d6c0-6e66-49b5-8e9e-e68ce76f4192_hifive-unmatched-schematics-v3.pdf - [2]: https://sifive.cdn.prismic.io/sifive/1a82e600-1f93-4f41-b2d8-86ed8b16acba_fu740-c000-manual-v1p6.pdf Changed in v3: - Convert the reference link to standard link. - Move the inverted function before taking the minimum value. - Change polarity check condition(high and low). - Pick the biggest period length possible that is not bigger than the requested period. Changed in v2: - Convert the reference link to standard link. - Fix typo: s/sifive unmatched:/sifive: unmatched:/. - Remove active-low from hifive-unleashed-a00.dts. - Include this reference link in the dts and pwm commit messages. Nylon Chen (2): riscv: dts: sifive: unleashed/unmatched: Remove PWM controlled LED's active-low properties pwm: sifive: change the PWM controlled LED algorithm arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts | 4 ---- arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts | 4 ---- drivers/pwm/pwm-sifive.c | 9 ++++++--- 3 files changed, 6 insertions(+), 11 deletions(-) -- 2.40.0
