netdev - Re: [PATCH net-next-2.6 v8 18/20] CAN : Optimize "if" condition in rx/tx processing

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Date:	Sun, 12 Dec 2010 16:16:45 +0100
From:	Marc Kleine-Budde <mkl@...gutronix.de>
To:	Tomoya MORINAGA <tomoya-linux@....okisemi.com>
CC:	Wolfgang Grandegger <wg@...ndegger.com>,
	socketcan-core@...ts.berlios.de, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, andrew.chih.howe.khor@...el.com,
	qi.wang@...el.com, margie.foster@...el.com, yong.y.wang@...el.com,
	kok.howg.ewe@...el.com, joel.clark@...el.com
Subject: Re: [PATCH net-next-2.6 v8 18/20] CAN : Optimize "if" condition in
 rx/tx	processing

On 12/07/2010 12:11 PM, Tomoya MORINAGA wrote:
> For reduce "if" condition, easy to read/understand the code,
> optimize "if" condition in rx/tx processing.
> 
> Signed-off-by: Tomoya MORINAGA <tomoya-linux@....okisemi.com>
Acked-by: Marc Kleine-Budde <mkl@...gutronix.de>
> ---
>  drivers/net/can/pch_can.c |   26 ++++++++++----------------
>  1 files changed, 10 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/net/can/pch_can.c b/drivers/net/can/pch_can.c
> index 8efbe35..dcd8f00 100644
> --- a/drivers/net/can/pch_can.c
> +++ b/drivers/net/can/pch_can.c
> @@ -746,19 +746,16 @@ static int pch_can_poll(struct napi_struct *napi, int quota)
>  
>  	if (int_stat == PCH_STATUS_INT) {
>  		reg_stat = ioread32(&priv->regs->stat);
> -		if (reg_stat & (PCH_BUS_OFF | PCH_LEC_ALL)) {
> -			if (reg_stat & PCH_BUS_OFF ||
> -			   (reg_stat & PCH_LEC_ALL) != PCH_LEC_ALL) {
> -				pch_can_error(ndev, reg_stat);
> -				quota--;
> -			}
> -		}
>  
> -		if (reg_stat & PCH_TX_OK)
> -			pch_can_bit_clear(&priv->regs->stat, PCH_TX_OK);
> +		if ((reg_stat & (PCH_BUS_OFF | PCH_LEC_ALL)) &&
> +		   ((reg_stat & PCH_LEC_ALL) != PCH_LEC_ALL)) {
> +			pch_can_error(ndev, reg_stat);
> +			quota--;
> +		}
>  
> -		if (reg_stat & PCH_RX_OK)
> -			pch_can_bit_clear(&priv->regs->stat, PCH_RX_OK);
> +		if (reg_stat & (PCH_TX_OK | PCH_RX_OK))
> +			pch_can_bit_clear(&priv->regs->stat,
> +					  reg_stat & (PCH_TX_OK | PCH_RX_OK));
>  
>  		int_stat = pch_can_int_pending(priv);
>  	}
> @@ -900,14 +897,13 @@ static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev)
>  	if (can_dropped_invalid_skb(ndev, skb))
>  		return NETDEV_TX_OK;
>  
> +	tx_obj_no = priv->tx_obj;
>  	if (priv->tx_obj == PCH_TX_OBJ_END) {
>  		if (ioread32(&priv->regs->treq2) & PCH_TREQ2_TX_MASK)
>  			netif_stop_queue(ndev);
>  
> -		tx_obj_no = priv->tx_obj;
>  		priv->tx_obj = PCH_TX_OBJ_START;
>  	} else {
> -		tx_obj_no = priv->tx_obj;
>  		priv->tx_obj++;
>  	}
>  
> @@ -926,9 +922,7 @@ static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev)
>  	id2 |= PCH_ID_MSGVAL;
>  
>  	/* If remote frame has to be transmitted.. */
> -	if (cf->can_id & CAN_RTR_FLAG)
> -		id2 &= ~PCH_ID2_DIR;
> -	else
> +	if (!(cf->can_id & CAN_RTR_FLAG))
>  		id2 |= PCH_ID2_DIR;
>  
>  	iowrite32(id2, &priv->regs->ifregs[1].id2);


-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
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