Re: [PATCH] Fix genphy_restart_aneg() for Micrel's ksz9031.

[Sascha Hauer <s.hauer@pengutronix.de>]

Hi Guillermo,

On Mon, Jun 13, 2016 at 07:29:15PM +0200, Guillermo Rodriguez Garcia wrote:
> From: grodriguez <guille.rodriguez@gmail.com>
> 
> Commit da89ee8f2e04 ("Center FLP timing at 16ms") breaks
> genphy_restart_aneg() for Micrel's ksz9031. According to the
> datasheet, the ksz9031 requires a wait of 1ms after clearing
> the PDOWN bit and before read/write access to any PHY registers.
> ---
>  drivers/net/phy/phy.c |    9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)

I must say that I am not overly happy with this patch as it leaks in phy
specific stuff into a somewhat generic function. Anyway, I see the need
for this patch and so I applied it.

Sascha

> 
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index 73176fb..ed69d9b 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -561,7 +561,7 @@ int phy_wait_aneg_done(struct phy_device *phydev)
>   */
>  int genphy_restart_aneg(struct phy_device *phydev)
>  {
> -	int ctl;
> +	int ctl, pdown;
>  
>  	ctl = phy_read(phydev, MII_BMCR);
>  
> @@ -574,6 +574,7 @@ int genphy_restart_aneg(struct phy_device *phydev)
>  	ctl &= ~(BMCR_ISOLATE);
>  
>  	/* Clear powerdown bit which eventually is set on some phys */
> +	pdown = ctl & BMCR_PDOWN;
>  	ctl &= ~BMCR_PDOWN;
>  
>  	ctl = phy_write(phydev, MII_BMCR, ctl);
> @@ -581,6 +582,12 @@ int genphy_restart_aneg(struct phy_device *phydev)
>  	if (ctl < 0)
>  		return ctl;
>  
> +	/* Micrel's ksz9031 (and perhaps others?): Changing the PDOWN bit
> +	 * from '1' to '0' generates an internal reset. Must wait a minimum
> +	 * of 1ms before read/write access to the PHY registers. */
> +	if (pdown)
> +		mdelay(1);
> +
>  	return 0;
>  }
>  
> -- 
> 1.7.9.5
> 
> 

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