[PATCH] fec: use interrupt for MDIO completion indication

[Bryan Wu]

Baruch,

Thanks for this patch, we tested on our i.MX51 board with Ubuntu. It works fine.

Wolfram, you can pick up this, too. -;)

-Bryan

On 07/12/2010 03:12 PM, Baruch Siach wrote:
> With the move to phylib (commit e6b043d) I was seeing sporadic "MDIO write
> timeout" messages. Measure of the actual time spent showed latency times of
> more than 1600us.
> 
> This patch uses the MII event indication of the FEC hardware to detect
> completion of MDIO transactions.
> 
> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
> ---
>  drivers/net/fec.c |   55 ++++++++++++++++++++++++----------------------------
>  1 files changed, 25 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/net/fec.c b/drivers/net/fec.c
> index edfff92..89f3393 100644
> --- a/drivers/net/fec.c
> +++ b/drivers/net/fec.c
> @@ -187,6 +187,7 @@ struct fec_enet_private {
>  	int	index;
>  	int	link;
>  	int	full_duplex;
> +	struct	completion mdio_done;
>  };
>  
>  static irqreturn_t fec_enet_interrupt(int irq, void * dev_id);
> @@ -205,7 +206,7 @@ static void fec_stop(struct net_device *dev);
>  #define FEC_MMFR_TA		(2 << 16)
>  #define FEC_MMFR_DATA(v)	(v & 0xffff)
>  
> -#define FEC_MII_TIMEOUT		10000
> +#define FEC_MII_TIMEOUT		1000 /* us */
>  
>  /* Transmitter timeout */
>  #define TX_TIMEOUT (2 * HZ)
> @@ -334,6 +335,11 @@ fec_enet_interrupt(int irq, void * dev_id)
>  			ret = IRQ_HANDLED;
>  			fec_enet_tx(dev);
>  		}
> +
> +		if (int_events & FEC_ENET_MII) {
> +			ret = IRQ_HANDLED;
> +			complete(&fep->mdio_done);
> +		}
>  	} while (int_events);
>  
>  	return ret;
> @@ -608,18 +614,13 @@ spin_unlock:
>  		phy_print_status(phy_dev);
>  }
>  
> -/*
> - * NOTE: a MII transaction is during around 25 us, so polling it...
> - */
>  static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
>  {
>  	struct fec_enet_private *fep = bus->priv;
> -	int timeout = FEC_MII_TIMEOUT;
> +	unsigned long time_left;
>  
>  	fep->mii_timeout = 0;
> -
> -	/* clear MII end of transfer bit*/
> -	writel(FEC_ENET_MII, fep->hwp + FEC_IEVENT);
> +	init_completion(&fep->mdio_done);
>  
>  	/* start a read op */
>  	writel(FEC_MMFR_ST | FEC_MMFR_OP_READ |
> @@ -627,13 +628,12 @@ static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
>  		FEC_MMFR_TA, fep->hwp + FEC_MII_DATA);
>  
>  	/* wait for end of transfer */
> -	while (!(readl(fep->hwp + FEC_IEVENT) & FEC_ENET_MII)) {
> -		cpu_relax();
> -		if (timeout-- < 0) {
> -			fep->mii_timeout = 1;
> -			printk(KERN_ERR "FEC: MDIO read timeout\n");
> -			return -ETIMEDOUT;
> -		}
> +	time_left = wait_for_completion_timeout(&fep->mdio_done,
> +			usecs_to_jiffies(FEC_MII_TIMEOUT));
> +	if (time_left == 0) {
> +		fep->mii_timeout = 1;
> +		printk(KERN_ERR "FEC: MDIO read timeout\n");
> +		return -ETIMEDOUT;
>  	}
>  
>  	/* return value */
> @@ -644,12 +644,10 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
>  			   u16 value)
>  {
>  	struct fec_enet_private *fep = bus->priv;
> -	int timeout = FEC_MII_TIMEOUT;
> +	unsigned long time_left;
>  
>  	fep->mii_timeout = 0;
> -
> -	/* clear MII end of transfer bit*/
> -	writel(FEC_ENET_MII, fep->hwp + FEC_IEVENT);
> +	init_completion(&fep->mdio_done);
>  
>  	/* start a read op */
>  	writel(FEC_MMFR_ST | FEC_MMFR_OP_READ |
> @@ -658,13 +656,12 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
>  		fep->hwp + FEC_MII_DATA);
>  
>  	/* wait for end of transfer */
> -	while (!(readl(fep->hwp + FEC_IEVENT) & FEC_ENET_MII)) {
> -		cpu_relax();
> -		if (timeout-- < 0) {
> -			fep->mii_timeout = 1;
> -			printk(KERN_ERR "FEC: MDIO write timeout\n");
> -			return -ETIMEDOUT;
> -		}
> +	time_left = wait_for_completion_timeout(&fep->mdio_done,
> +			usecs_to_jiffies(FEC_MII_TIMEOUT));
> +	if (time_left == 0) {
> +		fep->mii_timeout = 1;
> +		printk(KERN_ERR "FEC: MDIO write timeout\n");
> +		return -ETIMEDOUT;
>  	}
>  
>  	return 0;
> @@ -1222,7 +1219,8 @@ fec_restart(struct net_device *dev, int duplex)
>  	writel(0, fep->hwp + FEC_R_DES_ACTIVE);
>  
>  	/* Enable interrupts we wish to service */
> -	writel(FEC_ENET_TXF | FEC_ENET_RXF, fep->hwp + FEC_IMASK);
> +	writel(FEC_ENET_TXF | FEC_ENET_RXF | FEC_ENET_MII,
> +			fep->hwp + FEC_IMASK);
>  }
>  
>  static void
> @@ -1242,9 +1240,6 @@ fec_stop(struct net_device *dev)
>  	writel(1, fep->hwp + FEC_ECNTRL);
>  	udelay(10);
>  
> -	/* Clear outstanding MII command interrupts. */
> -	writel(FEC_ENET_MII, fep->hwp + FEC_IEVENT);
> -
>  	writel(fep->phy_speed, fep->hwp + FEC_MII_SPEED);
>  }
>