linux-kernel - Re: [PATCH 1/4] pwm: bcm-iproc: Remove impossible comparison when validating duty cycle

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Date:   Mon, 29 Jun 2020 21:45:51 +0200
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     thierry.reding@...il.com, linux-pwm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        Yendapally Reddy Dhananjaya Reddy 
        <yendapally.reddy@...adcom.com>,
        bcm-kernel-feedback-list@...adcom.com
Subject: Re: [PATCH 1/4] pwm: bcm-iproc: Remove impossible comparison when
 validating duty cycle

On Mon, Jun 29, 2020 at 01:47:49PM +0100, Lee Jones wrote:
> 'duty' here is an unsigned int, thus checking for <0 will always
> evaluate to false.
> 
> Fixes the following W=1 warning:
> 
>  drivers/pwm/pwm-bcm-iproc.c:147:12: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
> 
> Cc: Ray Jui <rjui@...adcom.com>
> Cc: Scott Branden <sbranden@...adcom.com>
> Cc: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@...adcom.com>
> Cc: bcm-kernel-feedback-list@...adcom.com
> Cc: linux-pwm@...r.kernel.org
> Signed-off-by: Lee Jones <lee.jones@...aro.org>
> ---
>  drivers/pwm/pwm-bcm-iproc.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
> index 1f829edd8ee70..46f0a45e9049c 100644
> --- a/drivers/pwm/pwm-bcm-iproc.c
> +++ b/drivers/pwm/pwm-bcm-iproc.c
> @@ -143,8 +143,7 @@ static int iproc_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>  		value = rate * state->duty_cycle;
>  		duty = div64_u64(value, div);
>  
> -		if (period < IPROC_PWM_PERIOD_MIN ||
> -		    duty < IPROC_PWM_DUTY_CYCLE_MIN)
> +		if (period < IPROC_PWM_PERIOD_MIN)
>  			return -EINVAL;
>  
>  		if (period <= IPROC_PWM_PERIOD_MAX &&

Acked-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>

Thanks
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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