linux-kernel - Re: [PATCH] pwm: sun4i: redundant assignment to variable pval

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Message-ID: <1080ef65-b089-937d-dfae-6f5484d4ed5f@canonical.com>
Date:   Wed, 2 Oct 2019 14:28:05 +0100
From:   Colin Ian King <colin.king@...onical.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>, linux-pwm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pwm: sun4i: redundant assignment to variable pval

On 02/10/2019 14:25, Dan Carpenter wrote:
> On Wed, Oct 02, 2019 at 11:08:44AM +0100, Colin King wrote:
>> From: Colin Ian King <colin.king@...onical.com>
>>
>> Variable pval is being assigned a value that is never read. The
>> assignment is redundant and hence can be removed.
>>
>> Addresses-Coverity: ("Unused value")
>> Signed-off-by: Colin Ian King <colin.king@...onical.com>
>> ---
>>  drivers/pwm/pwm-sun4i.c | 1 -
>>  1 file changed, 1 deletion(-)
>>
>> diff --git a/drivers/pwm/pwm-sun4i.c b/drivers/pwm/pwm-sun4i.c
>> index 6f5840a1a82d..53970d4ba695 100644
>> --- a/drivers/pwm/pwm-sun4i.c
>> +++ b/drivers/pwm/pwm-sun4i.c
>> @@ -156,7 +156,6 @@ static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm,
>>  	if (sun4i_pwm->data->has_prescaler_bypass) {
>>  		/* First, test without any prescaler when available */
>>  		prescaler = PWM_PRESCAL_MASK;
>> -		pval = 1;
>>  		/*
>>  		 * When not using any prescaler, the clock period in nanoseconds
>>  		 * is not an integer so round it half up instead of
> 
> Are you sure?  It looks used to me.

It's only read in a do_div() and before that it is being assigned:

                        pval = prescaler_table[prescaler];
                        div = clk_rate;
                        do_div(div, pval);

so the assigned value of pval = 1 is never read

Colin
> 
> regards,
> dan carpenter
>