linux-kernel - Re: [PATCH v4] pwm: bcm-iproc: handle clk_get

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Message-ID: <17848399-2b2d-b4f9-706b-94b3471c1e76@broadcom.com>
Date:   Fri, 24 Jul 2020 08:27:13 -0700
From:   Ray Jui <ray.jui@...adcom.com>
To:     Scott Branden <scott.branden@...adcom.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Lee Jones <lee.jones@...aro.org>
Cc:     Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
        linux-pwm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Rayagonda Kokatanur <rayagonda.kokatanur@...adcom.com>
Subject: Re: [PATCH v4] pwm: bcm-iproc: handle clk_get_rate() return

Hi Thierry/Uwe,

Do you have any further comment on this patch? If not, could you please
help to pick it up?

Thanks,

Ray

On 7/17/2020 9:46 PM, Scott Branden wrote:
> From: Rayagonda Kokatanur <rayagonda.kokatanur@...adcom.com>
> 
> Handle clk_get_rate() returning 0 to avoid possible division by zero.
> 
> Fixes: daa5abc41c80 ("pwm: Add support for Broadcom iProc PWM controller")
> Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@...adcom.com>
> Signed-off-by: Scott Branden <scott.branden@...adcom.com>
> Reviewed-by: Ray Jui <ray.jui@...adcom.com>
> 
> ---
> Changes from v3: fixed typo in commit message: Reviewed-off-by.
> Hopefully everything clean now.
> Changes from v2: update commit message to remove <= condition
> as clk_get_rate only returns value >= 0
> ---
>  drivers/pwm/pwm-bcm-iproc.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-bcm-iproc.c b/drivers/pwm/pwm-bcm-iproc.c
> index 1f829edd8ee7..d392a828fc49 100644
> --- a/drivers/pwm/pwm-bcm-iproc.c
> +++ b/drivers/pwm/pwm-bcm-iproc.c
> @@ -85,8 +85,6 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
>  	u64 tmp, multi, rate;
>  	u32 value, prescale;
>  
> -	rate = clk_get_rate(ip->clk);
> -
>  	value = readl(ip->base + IPROC_PWM_CTRL_OFFSET);
>  
>  	if (value & BIT(IPROC_PWM_CTRL_EN_SHIFT(pwm->hwpwm)))
> @@ -99,6 +97,13 @@ static void iproc_pwmc_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
>  	else
>  		state->polarity = PWM_POLARITY_INVERSED;
>  
> +	rate = clk_get_rate(ip->clk);
> +	if (rate == 0) {
> +		state->period = 0;
> +		state->duty_cycle = 0;
> +		return;
> +	}
> +
>  	value = readl(ip->base + IPROC_PWM_PRESCALE_OFFSET);
>  	prescale = value >> IPROC_PWM_PRESCALE_SHIFT(pwm->hwpwm);
>  	prescale &= IPROC_PWM_PRESCALE_MAX;
>