[RFC] net: allow FEC driver to not have attached PHY

[RFC] net: allow FEC driver to not have attached PHY

[Greg Ungerer]

Hi All,

I have a board with a ColdFire SoC on it with the built-in FEC
ethernet module. On this hardware the FEC eth output is directly
attached to a RTL8305 4-port 10/100 switch. There is no conventional
PHY, the FEC output is direct into the uplink port of the switch
chip.

This setup doesn't work after the FEC code was switch to using
phylib. The driver used to have code to bypass phy detection/setup
for this particular board. The phylib probe finds nothing, and of
course sets a no-link condition.

So, what is the cleanest way to support this?

The attached patch adds a config option to do this sort of generically
for the FEC driver. But I am wondering if there isn't a better way?

Regards
Greg


---

[RFC] net: allow FEC driver to not have attached PHY

At least one board using the FEC driver does not have a conventional
PHY attached to it, it is directly connected to a somewhat simple
ethernet switch (the board is the SnapGear/LITE, and the attached
4-port ethernet switch is a RealTek RTL8305). This switch does not
present the usual register interface of a PHY, it presents nothing.
So a PHY scan will find nothing.

After the FEC driver was changed to use phylib for supporting phys
it no longer works on this particular board/switch setup.

Add a config option to allow configuring the FEC driver to not expect
a PHY to be present.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
---
 drivers/net/Kconfig |    9 +++++++++
 drivers/net/fec.c   |    7 +++++++
 2 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 93494e2..ee44728 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -1934,6 +1934,15 @@ config FEC2
 	  Say Y here if you want to use the second built-in 10/100 Fast
 	  ethernet controller on some Motorola ColdFire processors.
 
+config FEC_NOPHY
+	bool "FEC has no attached PHY"
+	depends on FEC
+	help
+	  Some boards using the FEC driver may not have a PHY directly
+	  attached to it. Typically in this scenario the FEC output is
+	  directly connected to the input of an ethernet switch or hub.
+	  Say Y here if your hardware is like this.
+
 config FEC_MPC52xx
 	tristate "MPC52xx FEC driver"
 	depends on PPC_MPC52xx && PPC_BESTCOMM
diff --git a/drivers/net/fec.c b/drivers/net/fec.c
index 768b840..3637f89 100644
--- a/drivers/net/fec.c
+++ b/drivers/net/fec.c
@@ -910,6 +910,11 @@ fec_enet_open(struct net_device *dev)
 	if (ret)
 		return ret;
 
+#ifdef CONFIG_FEC_NOPHY
+	/* No PHY connected, assume link is always up */
+	fep->link = 1;
+	fec_restart(dev, 0);
+#else
 	/* Probe and connect to PHY when open the interface */
 	ret = fec_enet_mii_probe(dev);
 	if (ret) {
@@ -917,6 +922,8 @@ fec_enet_open(struct net_device *dev)
 		return ret;
 	}
 	phy_start(fep->phy_dev);
+#endif
+
 	netif_start_queue(dev);
 	fep->opened = 1;
 	return 0;

Re: [RFC] net: allow FEC driver to not have attached PHY

[Ben Hutchings]

On Thu, 2010-10-07 at 13:50 +1000, Greg Ungerer wrote:
> Hi All,
> 
> I have a board with a ColdFire SoC on it with the built-in FEC
> ethernet module. On this hardware the FEC eth output is directly
> attached to a RTL8305 4-port 10/100 switch. There is no conventional
> PHY, the FEC output is direct into the uplink port of the switch
> chip.
> 
> This setup doesn't work after the FEC code was switch to using
> phylib. The driver used to have code to bypass phy detection/setup
> for this particular board. The phylib probe finds nothing, and of
> course sets a no-link condition.
> 
> So, what is the cleanest way to support this?
> 
> The attached patch adds a config option to do this sort of generically
> for the FEC driver. But I am wondering if there isn't a better way?
[...]

Perhaps there could be a null PHY driver which does no MDIO and always
reports link-up at the expected speed and duplex.  We used something
like that in the sfc driver for some PHY-less boards (though we use our
own PHY abstraction, not phylib).

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

Re: [RFC] net: allow FEC driver to not have attached PHY

[Greg Ungerer]

Hi Ben,

On 07/10/10 23:11, Ben Hutchings wrote:
> On Thu, 2010-10-07 at 13:50 +1000, Greg Ungerer wrote:
>> Hi All,
>>
>> I have a board with a ColdFire SoC on it with the built-in FEC
>> ethernet module. On this hardware the FEC eth output is directly
>> attached to a RTL8305 4-port 10/100 switch. There is no conventional
>> PHY, the FEC output is direct into the uplink port of the switch
>> chip.
>>
>> This setup doesn't work after the FEC code was switch to using
>> phylib. The driver used to have code to bypass phy detection/setup
>> for this particular board. The phylib probe finds nothing, and of
>> course sets a no-link condition.
>>
>> So, what is the cleanest way to support this?
>>
>> The attached patch adds a config option to do this sort of generically
>> for the FEC driver. But I am wondering if there isn't a better way?
> [...]
>
> Perhaps there could be a null PHY driver which does no MDIO and always
> reports link-up at the expected speed and duplex.  We used something
> like that in the sfc driver for some PHY-less boards (though we use our
> own PHY abstraction, not phylib).

Looks like that is what the FIXED_PHY does.,

Thanks
Greg


------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg@snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close                             FAX:         +61 7 3217 5323
Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com

Re: [RFC] net: allow FEC driver to not have attached PHY

[Florian Fainelli]

Hi,

On Thursday 07 October 2010 05:50:16 Greg Ungerer wrote:
> Hi All,
> 
> I have a board with a ColdFire SoC on it with the built-in FEC
> ethernet module. On this hardware the FEC eth output is directly
> attached to a RTL8305 4-port 10/100 switch. There is no conventional
> PHY, the FEC output is direct into the uplink port of the switch
> chip.
> 
> This setup doesn't work after the FEC code was switch to using
> phylib. The driver used to have code to bypass phy detection/setup
> for this particular board. The phylib probe finds nothing, and of
> course sets a no-link condition.
> 
> So, what is the cleanest way to support this?

If phy detection fails and you cannot attach to a known PHY driver, you could 
register a fixed-PHY driver wich will report the link to be up. I had to do 
something like this for the cpmac driver[1] where various switches and 
external PHY configurations are supported.

[1]: 
https://dev.openwrt.org/browser/trunk/target/linux/ar7/patches-2.6.35/972-
cpmac_multi_probe.patch

> 
> The attached patch adds a config option to do this sort of generically
> for the FEC driver. But I am wondering if there isn't a better way?
> 
> Regards
> Greg
> 
> 
> ---
> 
> [RFC] net: allow FEC driver to not have attached PHY
> 
> At least one board using the FEC driver does not have a conventional
> PHY attached to it, it is directly connected to a somewhat simple
> ethernet switch (the board is the SnapGear/LITE, and the attached
> 4-port ethernet switch is a RealTek RTL8305). This switch does not
> present the usual register interface of a PHY, it presents nothing.
> So a PHY scan will find nothing.
> 
> After the FEC driver was changed to use phylib for supporting phys
> it no longer works on this particular board/switch setup.
> 
> Add a config option to allow configuring the FEC driver to not expect
> a PHY to be present.
> 
> Signed-off-by: Greg Ungerer <gerg@uclinux.org>
> ---
>  drivers/net/Kconfig |    9 +++++++++
>  drivers/net/fec.c   |    7 +++++++
>  2 files changed, 16 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
> index 93494e2..ee44728 100644
> --- a/drivers/net/Kconfig
> +++ b/drivers/net/Kconfig
> @@ -1934,6 +1934,15 @@ config FEC2
>  	  Say Y here if you want to use the second built-in 10/100 Fast
>  	  ethernet controller on some Motorola ColdFire processors.
> 
> +config FEC_NOPHY
> +	bool "FEC has no attached PHY"
> +	depends on FEC
> +	help
> +	  Some boards using the FEC driver may not have a PHY directly
> +	  attached to it. Typically in this scenario the FEC output is
> +	  directly connected to the input of an ethernet switch or hub.
> +	  Say Y here if your hardware is like this.
> +
>  config FEC_MPC52xx
>  	tristate "MPC52xx FEC driver"
>  	depends on PPC_MPC52xx && PPC_BESTCOMM
> diff --git a/drivers/net/fec.c b/drivers/net/fec.c
> index 768b840..3637f89 100644
> --- a/drivers/net/fec.c
> +++ b/drivers/net/fec.c
> @@ -910,6 +910,11 @@ fec_enet_open(struct net_device *dev)
>  	if (ret)
>  		return ret;
> 
> +#ifdef CONFIG_FEC_NOPHY
> +	/* No PHY connected, assume link is always up */
> +	fep->link = 1;
> +	fec_restart(dev, 0);
> +#else
>  	/* Probe and connect to PHY when open the interface */
>  	ret = fec_enet_mii_probe(dev);
>  	if (ret) {
> @@ -917,6 +922,8 @@ fec_enet_open(struct net_device *dev)
>  		return ret;
>  	}
>  	phy_start(fep->phy_dev);
> +#endif
> +
>  	netif_start_queue(dev);
>  	fep->opened = 1;
>  	return 0;
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [RFC] net: allow FEC driver to not have attached PHY

[Greg Ungerer]

Hi Florian,

On 07/10/10 23:24, Florian Fainelli wrote:
> On Thursday 07 October 2010 05:50:16 Greg Ungerer wrote:
>> Hi All,
>>
>> I have a board with a ColdFire SoC on it with the built-in FEC
>> ethernet module. On this hardware the FEC eth output is directly
>> attached to a RTL8305 4-port 10/100 switch. There is no conventional
>> PHY, the FEC output is direct into the uplink port of the switch
>> chip.
>>
>> This setup doesn't work after the FEC code was switch to using
>> phylib. The driver used to have code to bypass phy detection/setup
>> for this particular board. The phylib probe finds nothing, and of
>> course sets a no-link condition.
>>
>> So, what is the cleanest way to support this?
>
> If phy detection fails and you cannot attach to a known PHY driver, you could
> register a fixed-PHY driver wich will report the link to be up. I had to do
> something like this for the cpmac driver[1] where various switches and
> external PHY configurations are supported.
>
> [1]:
> https://dev.openwrt.org/browser/trunk/target/linux/ar7/patches-2.6.35/972-
> cpmac_multi_probe.patch

Ah yes, that looks like exactly what I need.
Thanks for the pointer.

Regards
Greg



>> The attached patch adds a config option to do this sort of generically
>> for the FEC driver. But I am wondering if there isn't a better way?
>>
>> Regards
>> Greg
>>
>>
>> ---
>>
>> [RFC] net: allow FEC driver to not have attached PHY
>>
>> At least one board using the FEC driver does not have a conventional
>> PHY attached to it, it is directly connected to a somewhat simple
>> ethernet switch (the board is the SnapGear/LITE, and the attached
>> 4-port ethernet switch is a RealTek RTL8305). This switch does not
>> present the usual register interface of a PHY, it presents nothing.
>> So a PHY scan will find nothing.
>>
>> After the FEC driver was changed to use phylib for supporting phys
>> it no longer works on this particular board/switch setup.
>>
>> Add a config option to allow configuring the FEC driver to not expect
>> a PHY to be present.
>>
>> Signed-off-by: Greg Ungerer<gerg@uclinux.org>
>> ---
>>   drivers/net/Kconfig |    9 +++++++++
>>   drivers/net/fec.c   |    7 +++++++
>>   2 files changed, 16 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
>> index 93494e2..ee44728 100644
>> --- a/drivers/net/Kconfig
>> +++ b/drivers/net/Kconfig
>> @@ -1934,6 +1934,15 @@ config FEC2
>>   	  Say Y here if you want to use the second built-in 10/100 Fast
>>   	  ethernet controller on some Motorola ColdFire processors.
>>
>> +config FEC_NOPHY
>> +	bool "FEC has no attached PHY"
>> +	depends on FEC
>> +	help
>> +	  Some boards using the FEC driver may not have a PHY directly
>> +	  attached to it. Typically in this scenario the FEC output is
>> +	  directly connected to the input of an ethernet switch or hub.
>> +	  Say Y here if your hardware is like this.
>> +
>>   config FEC_MPC52xx
>>   	tristate "MPC52xx FEC driver"
>>   	depends on PPC_MPC52xx&&  PPC_BESTCOMM
>> diff --git a/drivers/net/fec.c b/drivers/net/fec.c
>> index 768b840..3637f89 100644
>> --- a/drivers/net/fec.c
>> +++ b/drivers/net/fec.c
>> @@ -910,6 +910,11 @@ fec_enet_open(struct net_device *dev)
>>   	if (ret)
>>   		return ret;
>>
>> +#ifdef CONFIG_FEC_NOPHY
>> +	/* No PHY connected, assume link is always up */
>> +	fep->link = 1;
>> +	fec_restart(dev, 0);
>> +#else
>>   	/* Probe and connect to PHY when open the interface */
>>   	ret = fec_enet_mii_probe(dev);
>>   	if (ret) {
>> @@ -917,6 +922,8 @@ fec_enet_open(struct net_device *dev)
>>   		return ret;
>>   	}
>>   	phy_start(fep->phy_dev);
>> +#endif
>> +
>>   	netif_start_queue(dev);
>>   	fep->opened = 1;
>>   	return 0;
>> --
>> To unsubscribe from this list: send the line "unsubscribe netdev" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>


-- 
------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg@snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close                             FAX:         +61 7 3217 5323
Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com

Re: [RFC] net: allow FEC driver to not have attached PHY

[Simon Farnsworth]

Greg Ungerer wrote:

> 
> Hi All,
> 
> I have a board with a ColdFire SoC on it with the built-in FEC
> ethernet module. On this hardware the FEC eth output is directly
> attached to a RTL8305 4-port 10/100 switch. There is no conventional
> PHY, the FEC output is direct into the uplink port of the switch
> chip.
> 
> This setup doesn't work after the FEC code was switch to using
> phylib. The driver used to have code to bypass phy detection/setup
> for this particular board. The phylib probe finds nothing, and of
> course sets a no-link condition.
> 
> So, what is the cleanest way to support this?
> 
Is there anything that stops you using the fixed MDIO support in phylib 
(CONFIG_FIXED_PHY)? It seems to me to be intended for this sort of 
situation.

-- 
Simon