linux-kernel - Re: [PATCH v4 1/3] usb: chipidea: imx: Change switch order

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Date:   Wed, 21 Sep 2016 14:57:39 +0800
From:   Peter Chen <hzpeterchen@...il.com>
To:     Fabien Lahoudere <fabien.lahoudere@...labora.co.uk>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/3] usb: chipidea: imx: Change switch order

On Mon, Sep 19, 2016 at 01:45:38PM +0200, Fabien Lahoudere wrote:
> Each USB controller have different behaviour, so in order to avoid to have
> several "swicth(data->index)" and lock/unlock, we prefer to get the index
> switch and then test for features if they exist for this index.
> This patch also remove useless test of reg and val. Those two values cannot
> be NULL.

Sorry, I can't see the benefits of this change.
Considering certain controller doesn't have oc feature, with current
code it only needs one comparison (flag disable_oc), but with your
changes, it needs two comparisons. 

Peter
> 
> Signed-off-by: Fabien Lahoudere <fabien.lahoudere@...labora.co.uk>
> ---
>  drivers/usb/chipidea/usbmisc_imx.c | 38 ++++++++++++++++++++++++--------------
>  1 file changed, 24 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/usb/chipidea/usbmisc_imx.c b/drivers/usb/chipidea/usbmisc_imx.c
> index 20d02a5..9549821 100644
> --- a/drivers/usb/chipidea/usbmisc_imx.c
> +++ b/drivers/usb/chipidea/usbmisc_imx.c
> @@ -199,31 +199,41 @@ static int usbmisc_imx53_init(struct imx_usbmisc_data *data)
>  	val |= MX53_USB_PLL_DIV_24_MHZ;
>  	writel(val, usbmisc->base + MX53_USB_OTG_PHY_CTRL_1_OFFSET);
>  
> -	if (data->disable_oc) {
> -		spin_lock_irqsave(&usbmisc->lock, flags);
> -		switch (data->index) {
> -		case 0:
> +	spin_lock_irqsave(&usbmisc->lock, flags);
> +
> +	switch (data->index) {
> +	case 0:
> +		if (data->disable_oc) {
>  			reg = usbmisc->base + MX53_USB_OTG_PHY_CTRL_0_OFFSET;
>  			val = readl(reg) | MX53_BM_OVER_CUR_DIS_OTG;
> -			break;
> -		case 1:
> +			writel(val, reg);
> +		}
> +		break;
> +	case 1:
> +		if (data->disable_oc) {
>  			reg = usbmisc->base + MX53_USB_OTG_PHY_CTRL_0_OFFSET;
>  			val = readl(reg) | MX53_BM_OVER_CUR_DIS_H1;
> -			break;
> -		case 2:
> +			writel(val, reg);
> +		}
> +		break;
> +	case 2:
> +		if (data->disable_oc) {
>  			reg = usbmisc->base + MX53_USB_UH2_CTRL_OFFSET;
>  			val = readl(reg) | MX53_BM_OVER_CUR_DIS_UHx;
> -			break;
> -		case 3:
> +			writel(val, reg);
> +		}
> +		break;
> +	case 3:
> +		if (data->disable_oc) {
>  			reg = usbmisc->base + MX53_USB_UH3_CTRL_OFFSET;
>  			val = readl(reg) | MX53_BM_OVER_CUR_DIS_UHx;
> -			break;
> -		}
> -		if (reg && val)
>  			writel(val, reg);
> -		spin_unlock_irqrestore(&usbmisc->lock, flags);
> +		}
> +		break;
>  	}
>  
> +	spin_unlock_irqrestore(&usbmisc->lock, flags);
> +
>  	return 0;
>  }
>  
> -- 
> 2.1.4
> 

-- 

Best Regards,
Peter Chen