netdev - Re: [PATCH net-next 1/2] net: phy: aquantia: add rate

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Date:   Mon, 27 Jan 2020 09:42:41 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     "Madalin Bucur (OSS)" <madalin.bucur@....nxp.com>,
        "davem@...emloft.net" <davem@...emloft.net>
Cc:     "andrew@...n.ch" <andrew@...n.ch>,
        "hkallweit1@...il.com" <hkallweit1@...il.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "ykaukab@...e.de" <ykaukab@...e.de>
Subject: Re: [PATCH net-next 1/2] net: phy: aquantia: add rate_adaptation
 indication

On 1/22/20 11:38 PM, Madalin Bucur (OSS) wrote:
>> -----Original Message-----
>> From: Florian Fainelli <f.fainelli@...il.com>
>> Sent: Wednesday, January 22, 2020 7:58 PM
>> To: Madalin Bucur (OSS) <madalin.bucur@....nxp.com>; davem@...emloft.net
>> Cc: andrew@...n.ch; hkallweit1@...il.com; netdev@...r.kernel.org;
>> ykaukab@...e.de
>> Subject: Re: [PATCH net-next 1/2] net: phy: aquantia: add rate_adaptation
>> indication
>>
>> On 1/22/20 5:59 AM, Madalin Bucur wrote:
>>> The AQR PHYs are able to perform rate adaptation between
>>> the system interface and the line interfaces. When such
>>> a PHY is deployed, the ethernet driver should not limit
>>> the modes supported or advertised by the PHY. This patch
>>> introduces the bit that allows checking for this feature
>>> in the phy_device structure and its use for the Aquantia
>>> PHYs.
>>>
>>> Signed-off-by: Madalin Bucur <madalin.bucur@....nxp.com>
>>> ---
>>>  drivers/net/phy/aquantia_main.c | 3 +++
>>>  include/linux/phy.h             | 3 +++
>>>  2 files changed, 6 insertions(+)
>>>
>>> diff --git a/drivers/net/phy/aquantia_main.c
>> b/drivers/net/phy/aquantia_main.c
>>> index 975789d9349d..36fdd523b758 100644
>>> --- a/drivers/net/phy/aquantia_main.c
>>> +++ b/drivers/net/phy/aquantia_main.c
>>> @@ -209,6 +209,9 @@ static int aqr_config_aneg(struct phy_device
>> *phydev)
>>>  	u16 reg;
>>>  	int ret;
>>>
>>> +	/* add here as this is called for all devices */
>>> +	phydev->rate_adaptation = 1;
>>
>> How about introducing a new PHY_SUPPORTS_RATE_ADAPTATION flag and you
>> set that directly from the phy_driver entry? using the "flags" bitmask
>> instead of adding another structure member to phy_device?
> 
> I've looked at the phydev->dev_flags use, it seemed to me that mostly it
> is used to convey configuration options towards the PHY.

You read me incorrectly, I am suggesting using the phy_driver::flags
member, not the phy_device::dev_flags entry, please re-consider your
position.

> Another problem
> is that it's meaning seems to be opaque,  PHY specific. I wanted to avoid
> trampling on a certain PHY hardcoded value and I turned my attention to
> the bit fields in the phy_device. I noticed that there are already 12 bits
> so due to alignment, the added bit is not adding extra size to the struct.
>  
>>> +
>>>  	if (phydev->autoneg == AUTONEG_DISABLE)
>>>  		return genphy_c45_pma_setup_forced(phydev);
>>>
>>> diff --git a/include/linux/phy.h b/include/linux/phy.h
>>> index dd4a91f1feaa..2a5c202333fc 100644
>>> --- a/include/linux/phy.h
>>> +++ b/include/linux/phy.h
>>> @@ -387,6 +387,9 @@ struct phy_device {
>>>  	/* Interrupts are enabled */
>>>  	unsigned interrupts:1;
>>>
>>> +	/* Rate adaptation in the PHY */
>>> +	unsigned rate_adaptation:1;
>>> +
>>>  	enum phy_state state;
>>>
>>>  	u32 dev_flags;
>>>
>>
>>
>> --
>> Florian


-- 
Florian