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Date:   Fri, 14 Feb 2020 18:40:14 +0100
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Sasha Levin <sashal@...nel.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        yu kuai <yukuai3@...wei.com>,
        Thierry Reding <thierry.reding@...il.com>,
        linux-pwm@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.5 418/542] pwm: Remove set but not set variable
 'pwm'

Hello Sasha,

On Fri, Feb 14, 2020 at 10:46:50AM -0500, Sasha Levin wrote:
> From: yu kuai <yukuai3@...wei.com>
> 
> [ Upstream commit 9871abffc81048e20f02e15d6aa4558a44ad53ea ]
> 
> Fixes gcc '-Wunused-but-set-variable' warning:
> 
> 	drivers/pwm/pwm-pca9685.c: In function ‘pca9685_pwm_gpio_free’:
> 	drivers/pwm/pwm-pca9685.c:162:21: warning: variable ‘pwm’ set but not used [-Wunused-but-set-variable]
> 
> It is never used, and so can be removed. In that case, hold and release
> the lock 'pca->lock' can be removed since nothing will be done between
> them.
> 
> Fixes: e926b12c611c ("pwm: Clear chip_data in pwm_put()")
> Signed-off-by: yu kuai <yukuai3@...wei.com>
> Acked-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
> Signed-off-by: Thierry Reding <thierry.reding@...il.com>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  drivers/pwm/pwm-pca9685.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
> index 168684b02ebce..b07bdca3d510d 100644
> --- a/drivers/pwm/pwm-pca9685.c
> +++ b/drivers/pwm/pwm-pca9685.c
> @@ -159,13 +159,9 @@ static void pca9685_pwm_gpio_set(struct gpio_chip *gpio, unsigned int offset,
>  static void pca9685_pwm_gpio_free(struct gpio_chip *gpio, unsigned int offset)
>  {
>  	struct pca9685 *pca = gpiochip_get_data(gpio);
> -	struct pwm_device *pwm;
>  
>  	pca9685_pwm_gpio_set(gpio, offset, 0);
>  	pm_runtime_put(pca->chip.dev);
> -	mutex_lock(&pca->lock);
> -	pwm = &pca->chip.pwms[offset];
> -	mutex_unlock(&pca->lock);

Even though I bet this change won't introduce a regression, it only
fixes a harmless warning. So I wonder if it objectively qualifies to be
applied for stable.

Best regards
Uwe

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

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