netdev - Re: Q: force netif ON even when there is no real link ?

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Message-ID: <CAJ2oMhLPKfzi=-ZvXiHbG8rcEZc39nmU3qocvZc6NrmHwHQadg@mail.gmail.com>
Date:   Fri, 20 Apr 2018 17:01:19 +0300
From:   Ran Shalit <ranshalit@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     netdev@...r.kernel.org
Subject: Re: Q: force netif ON even when there is no real link ?

On Fri, Apr 20, 2018 at 3:14 PM, Ran Shalit <ranshalit@...il.com> wrote:
> On Fri, Apr 20, 2018 at 3:05 PM, Andrew Lunn <andrew@...n.ch> wrote:
>> On Fri, Apr 20, 2018 at 03:01:09PM +0300, Ran Shalit wrote:
>>> On Fri, Apr 20, 2018 at 2:55 PM, Andrew Lunn <andrew@...n.ch> wrote:
>>> > On Fri, Apr 20, 2018 at 11:44:14AM +0300, Ran Shalit wrote:
>>> >> Hello,
>>> >>
>>> >> We configure external switch in u-boot.
>>> >> The configuration is through mdio (cpu is mac and switch is phy).
>>> >>
>>> >> But in Linux we rather not implement any communication in mdio to
>>> >> switch, but it means that we then don't have the information of link
>>> >> state.
>>> >>
>>> >> Is it possible to force in Linux (by default in startup) Ethernet
>>> >> connectivity (netif_carrier_on, netif_wake_queue) even if there is no
>>> >> information of real link state ?
>>> >
>>> > Hi Ran
>>> >
>>> > Use a fixed-phy.
>>> >
>>>
>>> Hi Andrew,
>>>
>>> I'll check about fixed phy,
>>> but in general, is it a problem to have always netif_carrier_on, even
>>> when there is no link ?
>>
>> The link between the CPU and the switch should be up all the
>> time. That is the point of fixed-link.
>>
>
> I understand.
> But what about the mac driver,  does it just do netif_start_queue ?
>

By saying "mac driver", I mean Ethernet driver with fixed phy.

Regards,
Ranran

> Thanks
>
>
>>     Andrew