linux-kernel - Re: [PATCH] usb: dwc3-exynos fix unspecified suspend clk error handling

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Date:   Tue, 10 Jan 2017 13:05:58 +0100
From:   Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     Shuah Khan <shuahkh@....samsung.com>, balbi@...nel.org,
        gregkh@...uxfoundation.org, kgene@...nel.org, krzk@...nel.org,
        javier@....samsung.com, linux-samsung-soc@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: dwc3-exynos fix unspecified suspend clk error handling


Hi,

On Monday, January 09, 2017 07:21:31 PM Shuah Khan wrote:
> Fix dwc3_exynos_probe() to call clk_prepare_enable() only when suspend
> clock is specified. Call clk_disable_unprepare() from remove and probe
> error path only when susp_clk has been set from remove and probe error
> paths.

It is legal to call clk_prepare_enable() and clk_disable_unprepare()
for NULL clock.  Also your patch changes susp_clk handling while
leaves axius_clk handling (which also can be NULL) untouched.

Do you actually see some runtime problem with the current code?

If not then the patch should probably be dropped.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

> Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
> ---
>  drivers/usb/dwc3/dwc3-exynos.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-exynos.c b/drivers/usb/dwc3/dwc3-exynos.c
> index e27899b..f97a3d7 100644
> --- a/drivers/usb/dwc3/dwc3-exynos.c
> +++ b/drivers/usb/dwc3/dwc3-exynos.c
> @@ -131,8 +131,8 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
>  	if (IS_ERR(exynos->susp_clk)) {
>  		dev_info(dev, "no suspend clk specified\n");
>  		exynos->susp_clk = NULL;
> -	}
> -	clk_prepare_enable(exynos->susp_clk);
> +	} else
> +		clk_prepare_enable(exynos->susp_clk);
>  
>  	if (of_device_is_compatible(node, "samsung,exynos7-dwusb3")) {
>  		exynos->axius_clk = devm_clk_get(dev, "usbdrd30_axius_clk");
> @@ -196,7 +196,8 @@ static int dwc3_exynos_probe(struct platform_device *pdev)
>  	regulator_disable(exynos->vdd33);
>  err2:
>  	clk_disable_unprepare(exynos->axius_clk);
> -	clk_disable_unprepare(exynos->susp_clk);
> +	if (exynos->susp_clk)
> +		clk_disable_unprepare(exynos->susp_clk);
>  	clk_disable_unprepare(exynos->clk);
>  	return ret;
>  }
> @@ -210,7 +211,8 @@ static int dwc3_exynos_remove(struct platform_device *pdev)
>  	platform_device_unregister(exynos->usb3_phy);
>  
>  	clk_disable_unprepare(exynos->axius_clk);
> -	clk_disable_unprepare(exynos->susp_clk);
> +	if (exynos->susp_clk)
> +		clk_disable_unprepare(exynos->susp_clk);
>  	clk_disable_unprepare(exynos->clk);
>  
>  	regulator_disable(exynos->vdd33);