diff mbox series

[v7,2/3] pwm: sifive: change the PWM controlled LED algorithm

Message ID 20240123061748.8844-3-nylon.chen@sifive.com (mailing list archive)
State Superseded
Headers show
Series Change PWM-controlled LED pin active mode and algorithm | expand

Checks

Context Check Description
conchuod/vmtest-for-next-PR success PR summary
conchuod/patch-2-test-1 success .github/scripts/patches/tests/build_rv32_defconfig.sh
conchuod/patch-2-test-2 success .github/scripts/patches/tests/build_rv64_clang_allmodconfig.sh
conchuod/patch-2-test-3 success .github/scripts/patches/tests/build_rv64_gcc_allmodconfig.sh
conchuod/patch-2-test-4 success .github/scripts/patches/tests/build_rv64_nommu_k210_defconfig.sh
conchuod/patch-2-test-5 success .github/scripts/patches/tests/build_rv64_nommu_virt_defconfig.sh
conchuod/patch-2-test-6 success .github/scripts/patches/tests/checkpatch.sh
conchuod/patch-2-test-7 success .github/scripts/patches/tests/dtb_warn_rv64.sh
conchuod/patch-2-test-8 success .github/scripts/patches/tests/header_inline.sh
conchuod/patch-2-test-9 success .github/scripts/patches/tests/kdoc.sh
conchuod/patch-2-test-10 success .github/scripts/patches/tests/module_param.sh
conchuod/patch-2-test-11 success .github/scripts/patches/tests/verify_fixes.sh
conchuod/patch-2-test-12 success .github/scripts/patches/tests/verify_signedoff.sh

Commit Message

Nylon Chen Jan. 23, 2024, 6:17 a.m. UTC 
The `frac` variable represents the pulse inactive time, and the result
of this algorithm is the pulse active time. Therefore, we must reverse the result.

The reference is SiFive FU740-C000 Manual[0]

Link: https://sifive.cdn.prismic.io/sifive/1a82e600-1f93-4f41-b2d8-86ed8b16acba_fu740-c000-manual-v1p6.pdf [0]

Co-developed-by: Zong Li <zong.li@sifve.com>
Signed-off-by: Zong Li <zong.li@sifve.com>
Co-developed-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Nylon Chen <nylon.chen@sifive.com>
---
 drivers/pwm/pwm-sifive.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
index eabddb7c7820..b07c8598bb21 100644
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -113,6 +113,7 @@  static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	u32 duty, val;
 
 	duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
+	duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - duty;
 
 	state->enabled = duty > 0;
 
@@ -123,11 +124,10 @@  static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	state->period = ddata->real_period;
 	state->duty_cycle =
 		(u64)duty * ddata->real_period >> PWM_SIFIVE_CMPWIDTH;
-	state->polarity = PWM_POLARITY_INVERSED;
+	state->polarity = PWM_POLARITY_NORMAL;
 
 	return 0;
 }
-
 static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			    const struct pwm_state *state)
 {
@@ -139,7 +139,7 @@  static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	int ret = 0;
 	u32 frac;
 
-	if (state->polarity != PWM_POLARITY_INVERSED)
+	if (state->polarity != PWM_POLARITY_NORMAL)
 		return -EINVAL;
 
 	cur_state = pwm->state;
@@ -159,6 +159,7 @@  static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	frac = DIV64_U64_ROUND_CLOSEST(num, state->period);
 	/* The hardware cannot generate a 100% duty cycle */
 	frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
+	frac = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - frac;
 
 	mutex_lock(&ddata->lock);
 	if (state->period != ddata->approx_period) {