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bugfix i.mx6 pwm: prevent overflow of period_c * duty_ns

PATCH New Brecht Neyrinck 3 participants 3 messages May 6, 2015 – May 15, 2015

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Arm i.MX and Layerscape PWM
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Brecht Neyrinck

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#0 lore raw

PATCH 1/1 bugfix i.mx6 pwm: prevent overflow of period_c * duty_ns

Prevent overflow by casting duty_ns to ull first. This bug came up when trying to create a 200 Hz PWM

Signed-off-by Brecht Neyrinck <[email protected]>
---
 drivers/pwm/pwm-imx-util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/pwm/pwm-imx-util.c +1 -1
index f1d0b35..79d86028 100644
@@ -56,7 +56,7 @@ int pwm_imx_get_parms(int period_ns, int duty_ns, unsigned long *period_c,
 	*prescale = *period_c / 0x10000 + 1;
 
 	*period_c /= *prescale;
-	c = (unsigned long long)(*period_c * duty_ns);
+	c = *period_c * (unsigned long long)duty_ns;
 	do_div(c, period_ns);
 	*duty_c = c;
Signature · 14 lines
1.8.2.3




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#1 lore raw

PATCH 1/1 bugfix i.mx6 pwm: prevent overflow of period_c * duty_ns

Hello Brecht Neyrinck,

Am 06.05.2015 09:57, schrieb Brecht Neyrinck:

Quoted 6 lines

Prevent overflow by casting duty_ns to ull first. This bug came up when trying to create a 200 Hz PWM

Signed-off-by Brecht Neyrinck <[email protected]>
---
  drivers/pwm/pwm-imx-util.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

Thanks!

Acked-by Heiko Schocher<[email protected]>

bye,
Heiko

Signature · 2 lines
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
#2 lore raw

PATCH 1/1 bugfix i.mx6 pwm: prevent overflow of period_c * duty_ns

In reply to Brecht Neyrinck
Quoted 12 lines · Brecht Neyrinck

Prevent overflow by casting duty_ns to ull first. This bug came up when trying to create a 200 Hz PWM

Signed-off-by Brecht Neyrinck <[email protected]>
---
 drivers/pwm/pwm-imx-util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/pwm/pwm-imx-util.c +0 -0
index f1d0b35..79d86028 100644

drivers/pwm/pwm-imx-util.c int pwm_imx_get_parms(int period_ns, int duty_ns, unsigned long *period_c, · line 62

Quoted 8 lines
drivers/pwm/pwm-imx-util.c +1 -1
@@ -56,7 +56,7 @@ int pwm_imx_get_parms(int period_ns, int duty_ns, unsigned long *period_c,
 	*prescale = *period_c / 0x10000 + 1;
 
 	*period_c /= *prescale;
-	c = (unsigned long long)(*period_c * duty_ns);
+	c = *period_c * (unsigned long long)duty_ns;
 	do_div(c, period_ns);
 	*duty_c = c;

Applied to u-boot-imx, thanks !

Best regards,
Stefano Babic

Signature · 5 lines
=====================================================================
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de
=====================================================================