linux-kernel - Re: [PATCH] media: st_rc: Handle errors of clk_prepare

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Date:   Mon, 31 May 2021 11:09:37 +0100
From:   Sean Young <sean@...s.org>
To:     Evgeny Novikov <novikov@...ras.ru>
Cc:     Patrice Chotard <patrice.chotard@...s.st.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org, ldv-project@...uxtesting.org
Subject: Re: [PATCH] media: st_rc: Handle errors of clk_prepare_enable()

On Sat, May 15, 2021 at 03:39:09PM +0300, Evgeny Novikov wrote:
> Hadle errors of clk_prepare_enable() in st_rc_hardware_init() and its
> callers.
> 
> Found by Linux Driver Verification project (linuxtesting.org).
> 
> Signed-off-by: Evgeny Novikov <novikov@...ras.ru>
> ---
>  drivers/media/rc/st_rc.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/rc/st_rc.c b/drivers/media/rc/st_rc.c
> index 3237fef5d502..f524fcf55acf 100644
> --- a/drivers/media/rc/st_rc.c
> +++ b/drivers/media/rc/st_rc.c
> @@ -157,8 +157,9 @@ static irqreturn_t st_rc_rx_interrupt(int irq, void *data)
>  	return IRQ_HANDLED;
>  }
>  
> -static void st_rc_hardware_init(struct st_rc_device *dev)
> +static int st_rc_hardware_init(struct st_rc_device *dev)
>  {
> +	int ret;
>  	int baseclock, freqdiff;
>  	unsigned int rx_max_symbol_per = MAX_SYMB_TIME;
>  	unsigned int rx_sampling_freq_div;
> @@ -166,7 +167,10 @@ static void st_rc_hardware_init(struct st_rc_device *dev)
>  	/* Enable the IP */
>  	reset_control_deassert(dev->rstc);
>  
> -	clk_prepare_enable(dev->sys_clock);
> +	ret = clk_prepare_enable(dev->sys_clock);
> +	if (ret)
> +		return ret;

Now if probe or resume fails because of clk_prepare_enable() failing, no
error is logged. Please add a dev_err().

Thanks

Sean

> +
>  	baseclock = clk_get_rate(dev->sys_clock);
>  
>  	/* IRB input pins are inverted internally from high to low. */
> @@ -184,6 +188,8 @@ static void st_rc_hardware_init(struct st_rc_device *dev)
>  	}
>  
>  	writel(rx_max_symbol_per, dev->rx_base + IRB_MAX_SYM_PERIOD);
> +
> +	return 0;
>  }
>  
>  static int st_rc_remove(struct platform_device *pdev)
> @@ -287,7 +293,9 @@ static int st_rc_probe(struct platform_device *pdev)
>  
>  	rc_dev->dev = dev;
>  	platform_set_drvdata(pdev, rc_dev);
> -	st_rc_hardware_init(rc_dev);
> +	ret = st_rc_hardware_init(rc_dev);
> +	if (ret)
> +		goto err;
>  
>  	rdev->allowed_protocols = RC_PROTO_BIT_ALL_IR_DECODER;
>  	/* rx sampling rate is 10Mhz */
> @@ -359,6 +367,7 @@ static int st_rc_suspend(struct device *dev)
>  
>  static int st_rc_resume(struct device *dev)
>  {
> +	int ret;
>  	struct st_rc_device *rc_dev = dev_get_drvdata(dev);
>  	struct rc_dev	*rdev = rc_dev->rdev;
>  
> @@ -367,7 +376,10 @@ static int st_rc_resume(struct device *dev)
>  		rc_dev->irq_wake = 0;
>  	} else {
>  		pinctrl_pm_select_default_state(dev);
> -		st_rc_hardware_init(rc_dev);
> +		ret = st_rc_hardware_init(rc_dev);
> +		if (ret)
> +			return ret;
> +
>  		if (rdev->users) {
>  			writel(IRB_RX_INTS, rc_dev->rx_base + IRB_RX_INT_EN);
>  			writel(0x01, rc_dev->rx_base + IRB_RX_EN);
> -- 
> 2.26.2