ARM: S3C: PWM fix for low duty cycle
The pwm hardware only checks the compare register after a decrement,
so the pin never toggles if tcmp = tcnt.
This happens when a very low duty cycle is requested. Fix it by always
ensuring that tcmp < tcnt.
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
diff --git a/arch/arm/plat-s3c24xx/pwm.c b/arch/arm/plat-s3c24xx/pwm.c
index 0120b76..82a6d4d 100644
--- a/arch/arm/plat-s3c24xx/pwm.c
+++ b/arch/arm/plat-s3c24xx/pwm.c
@@ -246,6 +246,10 @@
tcmp = duty_ns / tin_ns;
tcmp = tcnt - tcmp;
+ /* the pwm hw only checks the compare register after a decrement,
+ so the pin never toggles if tcmp = tcnt */
+ if (tcmp == tcnt)
+ tcmp--;
pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);