[PATCH] net: rtl8169: remove unnecessary cache maintenance

[Lucas Stach]

Am Montag, den 05.01.2015, 20:19 +0300 schrieb Antony Pavlov:
> On Sun,  4 Jan 2015 22:09:05 +0100
> Lucas Stach <dev at lynxeye.de> wrote:
> 
> I suppose that this patch can make problems on MIPS with explicid cache handling.
> 
How would it?
This driver is ARM only for now (as we are using ARM MMU functions to
flush buffers) until someone gets around to properly implement generic
dma sync ops.

But even then MIPS knows about uncached memory types which is exactly
what should be returned for a dma coherent memory allocation.

Regards,
Lucas 
> > 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 at 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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> 
>