[PATCH][next] can: kvaser_pciefd: remove redundant negative check on trigger

[PATCH][next] can: kvaser_pciefd: remove redundant negative check on trigger

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The check to see if trigger is less than zero is always false, trigger
is always in the range 0..255.  Hence the check is redundant and can
be removed.

Addresses-Coverity: ("Logically dead code")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/net/can/kvaser_pciefd.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/net/can/kvaser_pciefd.c b/drivers/net/can/kvaser_pciefd.c
index 3af747cbbde4..68e00aad0810 100644
--- a/drivers/net/can/kvaser_pciefd.c
+++ b/drivers/net/can/kvaser_pciefd.c
@@ -652,9 +652,6 @@ static void kvaser_pciefd_pwm_stop(struct kvaser_pciefd_can *can)
 	top = (pwm_ctrl >> KVASER_PCIEFD_KCAN_PWM_TOP_SHIFT) & 0xff;
 
 	trigger = (100 * top + 50) / 100;
-	if (trigger < 0)
-		trigger = 0;
-
 	pwm_ctrl = trigger & 0xff;
 	pwm_ctrl |= (top & 0xff) << KVASER_PCIEFD_KCAN_PWM_TOP_SHIFT;
 	iowrite32(pwm_ctrl, can->reg_base + KVASER_PCIEFD_KCAN_PWM_REG);
-- 
2.20.1

Re: [PATCH][next] can: kvaser_pciefd: remove redundant negative check on trigger

[walter harms]

Am 25.07.2019 13:25, schrieb Colin King:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The check to see if trigger is less than zero is always false, trigger
> is always in the range 0..255.  Hence the check is redundant and can
> be removed.
> 
> Addresses-Coverity: ("Logically dead code")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/net/can/kvaser_pciefd.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/drivers/net/can/kvaser_pciefd.c b/drivers/net/can/kvaser_pciefd.c
> index 3af747cbbde4..68e00aad0810 100644
> --- a/drivers/net/can/kvaser_pciefd.c
> +++ b/drivers/net/can/kvaser_pciefd.c
> @@ -652,9 +652,6 @@ static void kvaser_pciefd_pwm_stop(struct kvaser_pciefd_can *can)
>  	top = (pwm_ctrl >> KVASER_PCIEFD_KCAN_PWM_TOP_SHIFT) & 0xff;
>  
>  	trigger = (100 * top + 50) / 100;
> -	if (trigger < 0)
> -		trigger = 0;
> -
	to be fair i do not understand the calculation here here.
	(100*top+50)/100 = top+50/100

	but seems to be int so it should be =top

	did i missunderstand something here ?

	re,
	 wh


>  	pwm_ctrl = trigger & 0xff;
>  	pwm_ctrl |= (top & 0xff) << KVASER_PCIEFD_KCAN_PWM_TOP_SHIFT;
>  	iowrite32(pwm_ctrl, can->reg_base + KVASER_PCIEFD_KCAN_PWM_REG);

Re: [PATCH][next] can: kvaser_pciefd: remove redundant negative check on trigger

[Colin Ian King]

On 25/07/2019 13:37, walter harms wrote:
> 
> 
> Am 25.07.2019 13:25, schrieb Colin King:
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> The check to see if trigger is less than zero is always false, trigger
>> is always in the range 0..255.  Hence the check is redundant and can
>> be removed.
>>
>> Addresses-Coverity: ("Logically dead code")
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>> ---
>>  drivers/net/can/kvaser_pciefd.c | 3 ---
>>  1 file changed, 3 deletions(-)
>>
>> diff --git a/drivers/net/can/kvaser_pciefd.c b/drivers/net/can/kvaser_pciefd.c
>> index 3af747cbbde4..68e00aad0810 100644
>> --- a/drivers/net/can/kvaser_pciefd.c
>> +++ b/drivers/net/can/kvaser_pciefd.c
>> @@ -652,9 +652,6 @@ static void kvaser_pciefd_pwm_stop(struct kvaser_pciefd_can *can)
>>  	top = (pwm_ctrl >> KVASER_PCIEFD_KCAN_PWM_TOP_SHIFT) & 0xff;
>>  
>>  	trigger = (100 * top + 50) / 100;
>> -	if (trigger < 0)
>> -		trigger = 0;
>> -
> 	to be fair i do not understand the calculation here here.
> 	(100*top+50)/100 = top+50/100
> 
> 	but seems to be int so it should be =top

Indeed it does not do anything, that does look like an unintentional
bug. Good catch.

> 
> 	did i missunderstand something here ?
> 
> 	re,
> 	 wh
> 
> 
>>  	pwm_ctrl = trigger & 0xff;
>>  	pwm_ctrl |= (top & 0xff) << KVASER_PCIEFD_KCAN_PWM_TOP_SHIFT;
>>  	iowrite32(pwm_ctrl, can->reg_base + KVASER_PCIEFD_KCAN_PWM_REG);