commit 66345c699a4344ff880d0420044e33e815a37f16
author Simon Glass <sjg@chromium.org> Wed Nov 03 13:21:33 2021 -0600
committer Minkyu Kang <mk7.kang@samsung.com> Tue Nov 09 11:57:22 2021 +0900
tree 287a938c5af8b07e0a62abd17e6fef8f395b20ec
parent 33b1f475caf35e6b70a2ec77d8baae83f07f0a63

exynos: pwm: Deal with a PWM at 100%

At present the counter never hits the comparitor in this case. Add a
special case.

This ensures that the snow backlight works when at full brightness.

Fixes: 76c2ff3e5fd video: backlight: fix pwm's duty cycle calculation

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

drivers/pwm/exynos_pwm.c

diff --git a/drivers/pwm/exynos_pwm.c b/drivers/pwm/exynos_pwm.c
index 1afaf78..609025d 100644
--- a/drivers/pwm/exynos_pwm.c
+++ b/drivers/pwm/exynos_pwm.c
@@ -43,6 +43,10 @@
 		tcnt = period_ns / rate_ns;
 		tcmp = duty_ns / rate_ns;
 		debug("%s: tcnt %u, tcmp %u\n", __func__, tcnt, tcmp);
+
+		/* Ensure that the comparitor will actually hit the target */
+		if (tcmp == tcnt)
+			tcmp = tcnt - 1;
 		offset = channel * 3;
 		writel(tcnt, &regs->tcntb0 + offset);
 		writel(tcmp, &regs->tcmpb0 + offset);