From: Nylon Chen <nylon.chen@sifive.com>
To: paul.walmsley@sifive.com, palmer@dabbelt.com,
linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org
Cc: nylon7717@gmail.com, zong.li@sifive.com, greentime.hu@sifive.com,
vincent.chen@sifive.com, Nylon Chen <nylon.chen@sifive.com>
Subject: [PATCH 0/2] Change PWM-controlled LED pin active mode and algorithm
Date: Fri, 13 Jan 2023 16:31:13 +0800 [thread overview]
Message-ID: <20230113083115.2590-1-nylon.chen@sifive.com> (raw)
According to the circuit diagram of User LEDs - RGB described in the
manual hifive-unmatched-schematics-v3.pdf[0].
The behavior of PWM is acitve-high.
According to the descriptionof PWM for pwmcmp in SiFive FU740-C000
Manual[1].
The pwm algorithm is (PW) pulse active time = (D) duty * (T) period[2].
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.
[0]:https://sifive-china.oss-cn-zhangjiakou.aliyuncs.com/HiFIve%20Unmatched/hifive-unmatched-schematics-v3.pdf
[1]:https://sifive-china.oss-cn-zhangjiakou.aliyuncs.com/HiFIve%20Unmatched/fu740-c000-manual-v1p2.pdf
[2]:https://en.wikipedia.org/wiki/Duty_cycle
Nylon Chen (2):
riscv: dts: sifive unmatched: Remove PWM controlled LED's active-low
properties
pwm: sifive: change the PWM controlled LED algorithm
arch/riscv/boot/dts/sifive/hifive-unmatched-a00.dts | 4 ----
drivers/pwm/pwm-sifive.c | 1 +
2 files changed, 1 insertion(+), 4 deletions(-)
--
2.36.1
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next reply other threads:[~2023-01-13 8:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-13 8:31 Nylon Chen [this message]
2023-01-13 8:31 ` [PATCH 1/2] riscv: dts: sifive unmatched: Remove PWM controlled LED's active-low properties Nylon Chen
2023-01-17 13:57 ` Conor Dooley
2023-01-13 8:31 ` [PATCH 2/2] pwm: sifive: change the PWM controlled LED algorithm Nylon Chen
2023-01-13 18:32 ` [PATCH 0/2] Change PWM-controlled LED pin active mode and algorithm Conor Dooley
2023-01-13 19:24 ` Jessica Clarke
2023-01-14 14:00 ` Conor Dooley
2023-01-18 2:32 ` Nylon Chen
2023-01-18 8:13 ` Conor Dooley
2023-01-17 9:32 ` Nylon Chen
2023-01-17 15:08 ` Ron Economos
2023-01-18 1:46 ` Ron Economos
2023-01-18 3:40 ` Ron Economos
2023-01-18 2:30 ` Nylon Chen
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