Patchwork [U-Boot,05/11,v3] Exynos: Avoid a divide by zero by specifying a non-zero period for pwm 4

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Submitter Akshay Saraswat
Date March 28, 2013, 2:32 p.m.
Message ID <>
Download mbox | patch
Permalink /patch/232042/
State Accepted
Delegated to: Minkyu Kang
Headers show


Akshay Saraswat - March 28, 2013, 2:32 p.m.
From: Gabe Black <>

The pwm_config function in the exynos pwm driver divides by its period
period parameter. A function was calling pwm_config with a 0ns period and a
0ns duty cycle. That doesn't actually make any sense physically, and results
in a divide by zero in the driver. This change changes the parameters to be a
100000ns period and duty cycle.

Test with command "sf probe 1:0; time sf read 40008000 0 1000".
Try with different numbers of bytes and see that sane values are obtained
Build and boot U-boot with this patch, backlight works properly.

Signed-off-by: Gabe Black <>
Signed-off-by: Akshay Saraswat <>
Acked-by: Simon Glass <>
Changes since v2:
        - Fixed typo paremters in commit message.

Changes since v1:
        - Added "Acked-by: Simon Glass".

 arch/arm/cpu/armv7/s5p-common/timer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


diff --git a/arch/arm/cpu/armv7/s5p-common/timer.c b/arch/arm/cpu/armv7/s5p-common/timer.c
index de61405..6a0fa58 100644
--- a/arch/arm/cpu/armv7/s5p-common/timer.c
+++ b/arch/arm/cpu/armv7/s5p-common/timer.c
@@ -58,7 +58,7 @@  int timer_init(void)
 	/* PWM Timer 4 */
 	pwm_init(4, MUX_DIV_4, 0);
-	pwm_config(4, 0, 0);
+	pwm_config(4, 100000, 100000);
 	/* Use this as the current monotonic time in us */