netdev - Re: [PATCH net-next 07/10] r8169: migrate speed

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Message-ID: <8d516fa8-30a5-df7e-737c-119d6e458d80@gmail.com>
Date:   Mon, 2 Jul 2018 23:31:02 +0200
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     David Miller <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>,
        Realtek linux nic maintainers <nic_swsd@...ltek.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 07/10] r8169: migrate speed_down function to
 phylib

On 02.07.2018 23:20, Andrew Lunn wrote:
>  On Mon, Jul 02, 2018 at 09:37:08PM +0200, Heiner Kallweit wrote:
>> Change rtl_speed_down() to use phylib.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
>> ---
>>  drivers/net/ethernet/realtek/r8169.c | 33 +++++++++++++---------------
>>  1 file changed, 15 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
>> index 311321ee..807fbc75 100644
>> --- a/drivers/net/ethernet/realtek/r8169.c
>> +++ b/drivers/net/ethernet/realtek/r8169.c
>> @@ -4240,6 +4240,10 @@ static void rtl8169_init_phy(struct net_device *dev, struct rtl8169_private *tp)
>>  		rtl_writephy(tp, 0x0b, 0x0000); //w 0x0b 15 0 0
>>  	}
>>  
>> +	/* We may have called rtl_speed_down before */
>> +	dev->phydev->advertising = dev->phydev->supported;
>> +	genphy_config_aneg(dev->phydev);
>> +
>>  	genphy_soft_reset(dev->phydev);
>>  
>>  	rtl8169_set_speed(dev, AUTONEG_ENABLE, SPEED_1000, DUPLEX_FULL,
>> @@ -4323,28 +4327,21 @@ static void rtl_init_mdio_ops(struct rtl8169_private *tp)
>>  	}
>>  }
>>  
>> +#define BASET10		(ADVERTISED_10baseT_Half | ADVERTISED_10baseT_Full)
>> +#define BASET100	(ADVERTISED_100baseT_Half | ADVERTISED_100baseT_Full)
>> +#define BASET1000	(ADVERTISED_1000baseT_Half | ADVERTISED_1000baseT_Full)
>> +
>>  static void rtl_speed_down(struct rtl8169_private *tp)
>>  {
>> -	u32 adv;
>> -	int lpa;
>> +	struct phy_device *phydev = tp->dev->phydev;
>> +	u32 adv = phydev->lp_advertising & phydev->supported;
>>  
>> -	rtl_writephy(tp, 0x1f, 0x0000);
>> -	lpa = rtl_readphy(tp, MII_LPA);
>> +	if (adv & BASET10)
>> +		phydev->advertising &= ~(BASET100 | BASET1000);
>> +	else if (adv & BASET100)
>> +		phydev->advertising &= ~BASET1000;
>>  
>> -	if (lpa & (LPA_10HALF | LPA_10FULL))
>> -		adv = ADVERTISED_10baseT_Half | ADVERTISED_10baseT_Full;
>> -	else if (lpa & (LPA_100HALF | LPA_100FULL))
>> -		adv = ADVERTISED_10baseT_Half | ADVERTISED_10baseT_Full |
>> -		      ADVERTISED_100baseT_Half | ADVERTISED_100baseT_Full;
>> -	else
>> -		adv = ADVERTISED_10baseT_Half | ADVERTISED_10baseT_Full |
>> -		      ADVERTISED_100baseT_Half | ADVERTISED_100baseT_Full |
>> -		      (tp->mii.supports_gmii ?
>> -		       ADVERTISED_1000baseT_Half |
>> -		       ADVERTISED_1000baseT_Full : 0);
>> -
>> -	rtl8169_set_speed(tp->dev, AUTONEG_ENABLE, SPEED_1000, DUPLEX_FULL,
>> -			  adv);
>> +	genphy_config_aneg(phydev);
>>  }
> 
> It probably it is me being too tired, but i don't get what this is
> doing? Changing the local advertisement based on what the remote is
> advertising. Why?
> 
It also took me some time to understand what this speed_down is doing.
If we suspend and wait for a WoL packet, then we don't have to burn all
the energy for a GBit connection. Therefore we switch to the lowest
speed supported by chip and link partner. This is done by removing
higher speeds from the advertised modes and restarting an autonego.

> 	Andrew
>