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

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

[Ran Shalit]

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 ?

Thank you,
ranran

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

[Andrew Lunn]

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.

    Andrew

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

[Ran Shalit]

On Fri, Apr 20, 2018 at 2:55 PM, Andrew Lunn <andrew@lunn.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 ?

Thank you,
ranran

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

[Andrew Lunn]

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@lunn.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.

    Andrew

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

[Ran Shalit]

On Fri, Apr 20, 2018 at 3:05 PM, Andrew Lunn <andrew@lunn.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@lunn.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 ?

Thanks


>     Andrew

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

[Ran Shalit]

On Fri, Apr 20, 2018 at 3:14 PM, Ran Shalit <ranshalit@gmail.com> wrote:
> On Fri, Apr 20, 2018 at 3:05 PM, Andrew Lunn <andrew@lunn.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@lunn.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

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

[Andrew Lunn]

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

The fixed-phy implements the usual PHY API. So the MAC driver just
sees a PHY which has a fixed speed, and is up.

     Andrew