netdev - Re: [PATCH 3/4] net: sfp: assume that LOS is not implemented if both LOS normal and inverted is set

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Date:   Wed, 30 Dec 2020 16:13:10 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Pali Rohár <pali@...nel.org>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Marek Behún <kabel@...nel.org>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] net: sfp: assume that LOS is not implemented if both
 LOS normal and inverted is set

On Wed, Dec 30, 2020 at 04:47:54PM +0100, Pali Rohár wrote:
> Some GPON SFP modules (e.g. Ubiquiti U-Fiber Instant) have set both
> SFP_OPTIONS_LOS_INVERTED and SFP_OPTIONS_LOS_NORMAL bits in their EEPROM.
> 
> Such combination of bits is meaningless so assume that LOS signal is not
> implemented.
> 
> This patch fixes link carrier for GPON SFP module Ubiquiti U-Fiber Instant.
> 
> Co-developed-by: Russell King <rmk+kernel@...linux.org.uk>
> Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>

No, this is not co-developed. The patch content is exactly what _I_
sent you, only the commit description is your own.

> Signed-off-by: Pali Rohár <pali@...nel.org>
> ---
>  drivers/net/phy/sfp.c | 36 ++++++++++++++++++++++--------------
>  1 file changed, 22 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
> index 73f3ecf15260..d47485ed239c 100644
> --- a/drivers/net/phy/sfp.c
> +++ b/drivers/net/phy/sfp.c
> @@ -1475,15 +1475,19 @@ static void sfp_sm_link_down(struct sfp *sfp)
>  
>  static void sfp_sm_link_check_los(struct sfp *sfp)
>  {
> -	unsigned int los = sfp->state & SFP_F_LOS;
> +	const __be16 los_inverted = cpu_to_be16(SFP_OPTIONS_LOS_INVERTED);
> +	const __be16 los_normal = cpu_to_be16(SFP_OPTIONS_LOS_NORMAL);
> +	__be16 los_options = sfp->id.ext.options & (los_inverted | los_normal);
> +	bool los = false;
>  
>  	/* If neither SFP_OPTIONS_LOS_INVERTED nor SFP_OPTIONS_LOS_NORMAL
> -	 * are set, we assume that no LOS signal is available.
> +	 * are set, we assume that no LOS signal is available. If both are
> +	 * set, we assume LOS is not implemented (and is meaningless.)
>  	 */
> -	if (sfp->id.ext.options & cpu_to_be16(SFP_OPTIONS_LOS_INVERTED))
> -		los ^= SFP_F_LOS;
> -	else if (!(sfp->id.ext.options & cpu_to_be16(SFP_OPTIONS_LOS_NORMAL)))
> -		los = 0;
> +	if (los_options == los_inverted)
> +		los = !(sfp->state & SFP_F_LOS);
> +	else if (los_options == los_normal)
> +		los = !!(sfp->state & SFP_F_LOS);
>  
>  	if (los)
>  		sfp_sm_next(sfp, SFP_S_WAIT_LOS, 0);
> @@ -1493,18 +1497,22 @@ static void sfp_sm_link_check_los(struct sfp *sfp)
>  
>  static bool sfp_los_event_active(struct sfp *sfp, unsigned int event)
>  {
> -	return (sfp->id.ext.options & cpu_to_be16(SFP_OPTIONS_LOS_INVERTED) &&
> -		event == SFP_E_LOS_LOW) ||
> -	       (sfp->id.ext.options & cpu_to_be16(SFP_OPTIONS_LOS_NORMAL) &&
> -		event == SFP_E_LOS_HIGH);
> +	const __be16 los_inverted = cpu_to_be16(SFP_OPTIONS_LOS_INVERTED);
> +	const __be16 los_normal = cpu_to_be16(SFP_OPTIONS_LOS_NORMAL);
> +	__be16 los_options = sfp->id.ext.options & (los_inverted | los_normal);
> +
> +	return (los_options == los_inverted && event == SFP_E_LOS_LOW) ||
> +	       (los_options == los_normal && event == SFP_E_LOS_HIGH);
>  }
>  
>  static bool sfp_los_event_inactive(struct sfp *sfp, unsigned int event)
>  {
> -	return (sfp->id.ext.options & cpu_to_be16(SFP_OPTIONS_LOS_INVERTED) &&
> -		event == SFP_E_LOS_HIGH) ||
> -	       (sfp->id.ext.options & cpu_to_be16(SFP_OPTIONS_LOS_NORMAL) &&
> -		event == SFP_E_LOS_LOW);
> +	const __be16 los_inverted = cpu_to_be16(SFP_OPTIONS_LOS_INVERTED);
> +	const __be16 los_normal = cpu_to_be16(SFP_OPTIONS_LOS_NORMAL);
> +	__be16 los_options = sfp->id.ext.options & (los_inverted | los_normal);
> +
> +	return (los_options == los_inverted && event == SFP_E_LOS_HIGH) ||
> +	       (los_options == los_normal && event == SFP_E_LOS_LOW);
>  }
>  
>  static void sfp_sm_fault(struct sfp *sfp, unsigned int next_state, bool warn)
> -- 
> 2.20.1
> 
> 

-- 
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