[RFC] net: dm9k: fix reset routine

[Sascha Hauer]

On Thu, Sep 11, 2014 at 03:20:01PM +0400, Antony Pavlov wrote:
> Based on Linux's commit:
> 
>     commit 09ee9f87d02e779e4fc3f5c29212c733d6d6e349
>     Author: Michael Abbott <michael.abbott at diamond.ac.uk>
>     Date:   Wed Oct 16 11:41:33 2013 +0300
> 
>         dm9000: Implement full reset of DM9000 network device
> 
>         A Davicom application note for the DM9000 network device recommends
>         performing software reset twice to correctly initialise the device.
>         Without this reset some devices fail to initialise correctly on
>         system startup.
> 
>  # define NCR_FDX	(1 << 3)
>  # define NCR_LBK	(3 << 1)
> +# define NCR_MAC_LBK	(1 << 1)
>  # define NCR_RST	(1 << 0)
>  
>  #define DM9K_NSR	0x01
> @@ -471,8 +472,28 @@ static void dm9k_reset(struct dm9k *priv)
>  	struct device_d *dev = priv->miibus.parent;
>  
>  	dev_dbg(dev, "%s\n", __func__);
> -	dm9k_iow(priv, DM9K_NCR, NCR_RST);
> -	udelay(1000);		/* delay 1ms */
> +
> +	/* Reset DM9000, see DM9000 Application Notes V1.22 Jun 11, 2004 page 29
> +	 * The essential point is that we have to do a double reset, and the
> +	 * instruction is to set LBK into MAC internal loopback mode.
> +	 */
> +
> +	/* Make all GPIO pins outputs */
> +	dm9k_iow(priv, DM9K_GPCR, 0x0F);
> +	/* Power internal PHY by writing 0 to GPIO0 pin */
> +	dm9k_iow(priv, DM9K_GPR, 0);
> +
> +	dm9k_iow(priv, DM9K_NCR, NCR_RST | NCR_MAC_LBK);
> +	udelay(100); /* Application note says at least 20 us */
> +	if (dm9k_ior(priv, DM9K_NCR) & NCR_RST)
> +		dev_err(dev, "dm9000 did not respond to first reset\n");
> +
> +	dm9k_iow(priv, DM9K_NCR, 0);
> +	dm9k_iow(priv, DM9K_NCR, NCR_RST | NCR_MAC_LBK);
> +	udelay(100);
> +
> +	if (dm9k_ior(priv, DM9K_NCR) & NCR_RST)
> +		dev_err(dev, "dm9000 did not respond to second reset\n");

How about using a loop to save a few bytes? Otherwise fine with me.

Sascha

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