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>

diff --git a/drivers/pwm/exynos_pwm.c b/drivers/pwm/exynos_pwm.c
index 1afaf78..609025d 100644 (file)
--- a/drivers/pwm/exynos_pwm.c
+++ b/drivers/pwm/exynos_pwm.c
@@ -43,6 +43,10 @@ static int exynos_pwm_set_config(struct udevice *dev, uint channel,
                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);