netdev - Re: [PATCH] net: phy: smsc: energy saving does not work without interrupts

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Message-ID: <20120321142834.GE3244@pengutronix.de>
Date:	Wed, 21 Mar 2012 15:28:34 +0100
From:	Wolfram Sang <w.sang@...gutronix.de>
To:	netdev@...r.kernel.org
Cc:	David Miller <davem@...emloft.net>,
	Giuseppe Cavallaro <peppe.cavallaro@...com>
Subject: Re: [PATCH] net: phy: smsc: energy saving does not work without
 interrupts

On Wed, Mar 21, 2012 at 01:08:27PM +0100, Wolfram Sang wrote:
> We discovered link detection failures using this PHY with the Freescale FEC
> which does not have interrupt support yet. Disabling the energy saving mode
> makes all go well. It should be possible to make this mode work without
> interrupts by adding some code dealing with the ENERGYON flag. Since adding
> interrupt support to the FEC driver seems to be the better solution for us, I
> want to at least make sure the PHY works reliably always. So, disable energy
> saving if there is no interrupt support.
> 
> Signed-off-by: Wolfram Sang <w.sang@...gutronix.de>
> Cc: Giuseppe Cavallaro <peppe.cavallaro@...com>
> ---
> 
> Giuseppe: Did you test with interrupts? Do you agree?
> 
> If Giuseppe is fine with the patch, this should probably be tagged for stable.
> 
>  drivers/net/phy/smsc.c |   22 ++++++++++++----------
>  1 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/net/phy/smsc.c b/drivers/net/phy/smsc.c
> index fc3e7e9..6dcf57a 100644
> --- a/drivers/net/phy/smsc.c
> +++ b/drivers/net/phy/smsc.c
> @@ -43,16 +43,18 @@ static int smsc_phy_ack_interrupt(struct phy_device *phydev)
>  
>  static int smsc_phy_config_init(struct phy_device *phydev)
>  {
> -	int rc = phy_read(phydev, MII_LAN83C185_CTRL_STATUS);
> -	if (rc < 0)
> -		return rc;
> -
> -	/* Enable energy detect mode for this SMSC Transceivers */
> -	rc = phy_write(phydev, MII_LAN83C185_CTRL_STATUS,
> -		       rc | MII_LAN83C185_EDPWRDOWN);
> -	if (rc < 0)
> -		return rc;
> -
> +	/* TODO: add code to make EDPWRDOWN work without interrupts */
> +	if (PHY_INTERRUPT_ENABLED == phydev->interrupts) {

Gnarg, that should probably be:

+	if (phydev->irq != PHY_POLL) ...

since interrupts maybe not enabled at this point? Will resend, but will
wait some more for comments.

> +		int rc = phy_read(phydev, MII_LAN83C185_CTRL_STATUS);
> +		if (rc < 0)
> +			return rc;
> +
> +		/* Enable energy detect mode for this SMSC Transceivers */
> +		rc = phy_write(phydev, MII_LAN83C185_CTRL_STATUS,
> +			       rc | MII_LAN83C185_EDPWRDOWN);
> +		if (rc < 0)
> +			return rc;
> +	}
>  	return smsc_phy_ack_interrupt (phydev);
>  }
>  
> -- 
> 1.7.9.1
> 

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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