From: Sebastian Frias <sf84@laposte•net>
To: "Florian Fainelli" <f.fainelli@gmail•com>,
"Måns Rullgård" <mans@mansr•com>
Cc: "David S. Miller" <davem@davemloft•net>,
netdev <netdev@vger•kernel.org>,
LKML <linux-kernel@vger•kernel.org>, Mason <slash.tmp@free•fr>,
Andrew Lunn <andrew@lunn•ch>
Subject: Re: [PATCH 1/2] net: ethernet: nb8800: Do not apply TX delay at MAC level
Date: Mon, 14 Nov 2016 14:22:46 +0100 [thread overview]
Message-ID: <5829BAA6.20905@laposte.net> (raw)
In-Reply-To: <0fc519a7-6e42-de55-7a4a-c7dc9d64c5db@gmail.com>
On 11/09/2016 06:03 PM, Florian Fainelli wrote:
> On 11/09/2016 05:02 AM, Sebastian Frias wrote:
>> On 11/04/2016 05:49 PM, Måns Rullgård wrote:
>>>>> But when doing so, both the Atheros 8035 and the Aurora NB8800 drivers
>>>>> will apply the delay.
>>>>>
>>>>> I think a better way of dealing with this is that both, PHY and MAC
>>>>> drivers exchange information so that the delay is applied only once.
>>>>
>>>> Exchange what information? The PHY device interface (phydev->interface)
>>>> conveys the needed information for both entities.
>>>
>>> There doesn't seem to be any consensus among the drivers regarding where
>>> the delay should be applied. Since only a few drivers, MAC or PHY, act
>>> on this property, most combinations still work by chance. It is common
>>> for boards to set the delay at the PHY using external config pins so no
>>> software setup is required (although I have one Sigma based board that
>>> gets this wrong). I suspect if drivers/net/ethernet/broadcom/genet were
>>> used with one of the four PHY drivers that also set the delay based on
>>> this DT property, things would go wrong.
>>>
>>
>> Exactly, what about a patch like (I can make a formal submission, even
>> merge it with the patch discussed in this thread, consider this a RFC):
>
> I really don't see a point in doing this when we can just clarify what
> phydev->interface does and already have the knowledge that we need
> without introducing additional flags in the phy driver.
>
Ok, so who can clarify what "phydev->interface" does, especially in the
context of this discussion?
What happens when a TX delay must be applied and:
- both the PHY and the MAC support the delay
- only the PHY supports the delay
- only the MAC supports the delay
Best regards,
Sebastian
prev parent reply other threads:[~2016-11-14 13:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-04 15:02 [PATCH 1/2] net: ethernet: nb8800: Do not apply TX delay at MAC level Sebastian Frias
2016-11-04 15:11 ` Andrew Lunn
2016-11-04 15:27 ` Måns Rullgård
2016-11-04 15:29 ` Sebastian Frias
2016-11-04 15:18 ` Måns Rullgård
2016-11-04 15:36 ` Sebastian Frias
2016-11-04 16:28 ` Florian Fainelli
2016-11-04 16:49 ` Måns Rullgård
2016-11-09 13:02 ` Sebastian Frias
2016-11-09 17:03 ` Florian Fainelli
2016-11-14 13:22 ` Sebastian Frias [this message]
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