Re: [PATCH] net: rtl8169: remove unnecessary cache maintenance

[Antony Pavlov <antonynpavlov@gmail.com>]

On Sun,  4 Jan 2015 22:09:05 +0100
Lucas Stach <dev@lynxeye.de> wrote:

I suppose that this patch can make problems on MIPS with explicid cache handling.

> The buffer descriptors are allocated from coherent memory, so there
> is no cache maintenance needed. Only tell the compiler that the descriptors
> can be modified by the hardware.
> 
> Signed-off-by: Lucas Stach <dev@lynxeye.de>
> ---
>  drivers/net/rtl8169.c | 24 +++++-------------------
>  1 file changed, 5 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/net/rtl8169.c b/drivers/net/rtl8169.c
> index 5702900..19f5763 100644
> --- a/drivers/net/rtl8169.c
> +++ b/drivers/net/rtl8169.c
> @@ -50,11 +50,11 @@ struct rtl8169_priv {
>  	struct pci_dev		*pci_dev;
>  	int			chipset;
>  
> -	struct bufdesc		*tx_desc;
> +	volatile struct bufdesc	*tx_desc;
>  	void			*tx_buf;
>  	unsigned int		cur_tx;
>  
> -	struct bufdesc		*rx_desc;
> +	volatile struct bufdesc	*rx_desc;
>  	void			*rx_buf;
>  	unsigned int		cur_rx;
>  
> @@ -250,10 +250,6 @@ static void rtl8169_init_ring(struct rtl8169_priv *priv)
>  		priv->rx_desc[i].buf_addr =
>  				virt_to_phys(priv->rx_buf + i * PKT_BUF_SIZE);
>  	}
> -
> -	dma_flush_range((unsigned long)priv->rx_desc,
> -			(unsigned long)priv->rx_desc +
> -			NUM_RX_DESC * sizeof(struct bufdesc));
>  }
>  
>  static void rtl8169_hw_start(struct rtl8169_priv *priv)
> @@ -386,14 +382,10 @@ static int rtl8169_eth_send(struct eth_device *edev, void *packet,
>  			((packet_length > ETH_ZLEN) ? packet_length : ETH_ZLEN);
>  	}
>  
> -	dma_flush_range((unsigned long)&priv->tx_desc[entry],
> -			(unsigned long)&priv->tx_desc[entry + 1]);
> -
>  	RTL_W8(priv, TxPoll, 0x40);
> -	do {
> -		dma_inv_range((unsigned long)&priv->tx_desc[entry],
> -		              (unsigned long)&priv->tx_desc[entry + 1]);
> -	} while (priv->tx_desc[entry].status & BD_STAT_OWN);
> +
> +	while (priv->tx_desc[entry].status & BD_STAT_OWN)
> +		;
>  
>  	priv->cur_tx++;
>  
> @@ -408,9 +400,6 @@ static int rtl8169_eth_rx(struct eth_device *edev)
>  
>  	entry = priv->cur_rx % NUM_RX_DESC;
>  
> -	dma_inv_range((unsigned long)&priv->rx_desc[entry],
> -	              (unsigned long)&priv->rx_desc[entry + 1]);
> -
>  	if ((priv->rx_desc[entry].status & BD_STAT_OWN) == 0) {
>  		if (!(priv->rx_desc[entry].status & BD_STAT_RX_RES)) {
>  			pkt_size = (priv->rx_desc[entry].status & 0x1fff) - 4;
> @@ -441,9 +430,6 @@ static int rtl8169_eth_rx(struct eth_device *edev)
>  			priv->rx_desc[entry].buf_addr =
>  				virt_to_phys(priv->rx_buf +
>  				             entry * PKT_BUF_SIZE);
> -
> -			dma_flush_range((unsigned long)&priv->rx_desc[entry],
> -			                (unsigned long)&priv->rx_desc[entry + 1]);
>  		} else {
>  			dev_err(&edev->dev, "rx error\n");
>  		}
> -- 
> 2.1.0
> 
> 
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-- 
-- 
Best regards,
  Antony Pavlov

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