davinci-mdio: failing to connect to PHY

davinci-mdio: failing to connect to PHY

[Petr Kulhavy]

Hi,

I'm experiencing a peculiar problem with PHY communication in the 
current davinci-mdio.c driver.
After upgrading from kernel 3.17 to 4.5 my DT based AM1808 board started 
having issues with the PHY communication.
The MAC is detected, the MDIO is detected, the PHY is detected 
(twice?!?!), however there is no data being sent/received and the after 
issuing "ifdown -a" the MDIO starts spitting out messages that it cannot 
connect to the PHY:

net eth0: could not connect to phy davinci_mdio.0:00
davinci_mdio davinci_mdio.0: resetting idled controller


I'm using a single Micrel KSZ8081 PHY connected via RMII using the 
default PHY address 0x01.
Here is the dmesg excerpt related to mdio:

davinci_mdio davinci_mdio.0: Runtime PM disabled, clock forced on.
davinci_mdio davinci_mdio.0: davinci mdio revision 1.5
davinci_mdio davinci_mdio.0: detected phy mask fffffffc
libphy: davinci_mdio.0: probed
davinci_mdio davinci_mdio.0: phy[0]: device davinci_mdio.0:00, driver 
Micrel KSZ8081 or KSZ8091
davinci_mdio davinci_mdio.0: phy[1]: device davinci_mdio.0:01, driver 
Micrel KSZ8081 or KSZ8091
davinci_mdio davinci_mdio.0: resetting idled controller
Micrel KSZ8081 or KSZ8091 davinci_mdio.0:00: failed to disable NAND tree 
mode
Micrel KSZ8081 or KSZ8091 davinci_mdio.0:00: attached PHY driver [Micrel 
KSZ8081 or KSZ8091] (mii_bus:phy_addr=davinci_mdio.0:00, irq=-1)


After a soft-reboot the MDIO uses a different PHY mask fffffffd, detects 
correctly only one PHY at address 1 (this is the default address) and 
the networking works:

davinci_mdio davinci_mdio.0: Runtime PM disabled, clock forced on.
davinci_mdio davinci_mdio.0: davinci mdio revision 1.5
davinci_mdio davinci_mdio.0: detected phy mask fffffffd
libphy: davinci_mdio.0: probed
davinci_mdio davinci_mdio.0: phy[1]: device davinci_mdio.0:01, driver 
Micrel KSZ8081 or KSZ8091
davinci_mdio davinci_mdio.0: resetting idled controller
Micrel KSZ8081 or KSZ8091 davinci_mdio.0:01: attached PHY driver [Micrel 
KSZ8081 or KSZ8091] (mii_bus:phy_addr=davinci_mdio.0:01, irq=-1)


I'm wondering what the problem is and why the PHY mask is different 
after power-up and after a soft reboot.
Also it's not clear to me why this set-up worked with kernel 3.17 even 
if it was detecting the PHY twice exactly the same way.
How does the mask relate to the PHY address and how is it calculated?

Thanks
Petr

Re: davinci-mdio: failing to connect to PHY

[Andrew Lunn]

On Mon, Apr 04, 2016 at 10:18:30AM +0200, Petr Kulhavy wrote:
> Hi,
> 
> I'm experiencing a peculiar problem with PHY communication in the
> current davinci-mdio.c driver.
> After upgrading from kernel 3.17 to 4.5 my DT based AM1808 board
> started having issues with the PHY communication.
> The MAC is detected, the MDIO is detected, the PHY is detected
> (twice?!?!), however there is no data being sent/received and the
> after issuing "ifdown -a" the MDIO starts spitting out messages that
> it cannot connect to the PHY:
> 
> net eth0: could not connect to phy davinci_mdio.0:00
> davinci_mdio davinci_mdio.0: resetting idled controller
> 
> 
> I'm using a single Micrel KSZ8081 PHY connected via RMII using the
> default PHY address 0x01.
> Here is the dmesg excerpt related to mdio:
> 
> davinci_mdio davinci_mdio.0: Runtime PM disabled, clock forced on.
> davinci_mdio davinci_mdio.0: davinci mdio revision 1.5
> davinci_mdio davinci_mdio.0: detected phy mask fffffffc
> libphy: davinci_mdio.0: probed
> davinci_mdio davinci_mdio.0: phy[0]: device davinci_mdio.0:00,
> driver Micrel KSZ8081 or KSZ8091
> davinci_mdio davinci_mdio.0: phy[1]: device davinci_mdio.0:01,
> driver Micrel KSZ8081 or KSZ8091
> davinci_mdio davinci_mdio.0: resetting idled controller
> Micrel KSZ8081 or KSZ8091 davinci_mdio.0:00: failed to disable NAND
> tree mode
> Micrel KSZ8081 or KSZ8091 davinci_mdio.0:00: attached PHY driver
> [Micrel KSZ8081 or KSZ8091] (mii_bus:phy_addr=davinci_mdio.0:00,
> irq=-1)
> 
> 
> After a soft-reboot the MDIO uses a different PHY mask fffffffd,
> detects correctly only one PHY at address 1 (this is the default
> address) and the networking works:
 
Hi Petr

You might want to take a look at:

http://lxr.free-electrons.com/source/drivers/net/ethernet/ti/davinci_mdio.c#L137

It seems to be asking the hardware about the phy mask.

   Andrew

Re: davinci-mdio: failing to connect to PHY

[Petr Kulhavy]

On 04.04.2016 14:31, Andrew Lunn wrote:
>   
> Hi Petr
>
> You might want to take a look at:
>
> http://lxr.free-electrons.com/source/drivers/net/ethernet/ti/davinci_mdio.c#L137
>
> It seems to be asking the hardware about the phy mask.
>
>     Andrew

Hi Andrew,

thanks a lot for the link. In the meantime I've understood the issue 
better. It is due to the fact that the PHY is pin-strapped to address 1 
and broadcast (at address 0) is  enabled. The Micrel driver's 
config_init() disables the broadcast and the PHY stops responding, which 
causes the troubles. The kernel 3.17 didn't disable the broadcast and 
therefore it worked.

I'm wondering how to solve or workaround this...

Petr

Re: davinci-mdio: failing to connect to PHY

[Andrew Lunn]

On Mon, Apr 04, 2016 at 03:50:02PM +0200, Petr Kulhavy wrote:
> 
> 
> On 04.04.2016 14:31, Andrew Lunn wrote:
> >Hi Petr
> >
> >You might want to take a look at:
> >
> >http://lxr.free-electrons.com/source/drivers/net/ethernet/ti/davinci_mdio.c#L137
> >
> >It seems to be asking the hardware about the phy mask.
> >
> >    Andrew
> 
> Hi Andrew,
> 
> thanks a lot for the link. In the meantime I've understood the issue
> better. It is due to the fact that the PHY is pin-strapped to
> address 1 and broadcast (at address 0) is  enabled. The Micrel
> driver's config_init() disables the broadcast and the PHY stops
> responding, which causes the troubles. The kernel 3.17 didn't
> disable the broadcast and therefore it worked.
> 
> I'm wondering how to solve or workaround this...

One option is in your device tree is to explicitly list the phy on
your mdio bus. Something like:

&mdio {
        status = "okay";

        ethphy0: ethernet-phy@1 {
                reg = <1>;
        };
};

This alone might be sufficient. If not, you need to reference the phy
via a phandle in the ethernet node.


&eth0 {
        status = "okay";
        phy-handle = <&ethphy0>;
};

	Andrew

Re: davinci-mdio: failing to connect to PHY

[Petr Kulhavy]

On 04.04.2016 15:58, Andrew Lunn wrote:
> On Mon, Apr 04, 2016 at 03:50:02PM +0200, Petr Kulhavy wrote:
>> Hi Andrew,
>>
>> thanks a lot for the link. In the meantime I've understood the issue
>> better. It is due to the fact that the PHY is pin-strapped to
>> address 1 and broadcast (at address 0) is  enabled. The Micrel
>> driver's config_init() disables the broadcast and the PHY stops
>> responding, which causes the troubles. The kernel 3.17 didn't
>> disable the broadcast and therefore it worked.
>>
>> I'm wondering how to solve or workaround this...
> One option is in your device tree is to explicitly list the phy on
> your mdio bus. Something like:
>
> &mdio {
>          status = "okay";
>
>          ethphy0: ethernet-phy@1 {
>                  reg = <1>;
>          };
> };
>
> This alone might be sufficient. If not, you need to reference the phy
> via a phandle in the ethernet node.
>
>
> &eth0 {
>          status = "okay";
>          phy-handle = <&ethphy0>;
> };
>
> 	Andrew
Thanks a lot, I'm going to try it out right now!

Cheers
Petr

davinci-mdio: failing to connect to PHY

[Petr Kulhavy]

Hi,

I'm experiencing a peculiar problem with PHY communication in the 
current davinci-mdio.c driver.
After upgrading from kernel 3.17 to 4.5 my DT based AM1808 board started 
having issues with the PHY communication.
The MAC is detected, the MDIO is detected, the PHY is detected 
(twice?!?!), however there is no data being sent/received and the after 
issuing "ifdown -a" the MDIO starts spitting out messages that it cannot 
connect to the PHY:

net eth0: could not connect to phy davinci_mdio.0:00
davinci_mdio davinci_mdio.0: resetting idled controller


I'm using a single Micrel KSZ8081 PHY connected via RMII.
Here is the dmesg excerpt related to mdio:

davinci_mdio davinci_mdio.0: Runtime PM disabled, clock forced on.
davinci_mdio davinci_mdio.0: davinci mdio revision 1.5
davinci_mdio davinci_mdio.0: detected phy mask fffffffc
libphy: davinci_mdio.0: probed
davinci_mdio davinci_mdio.0: phy[0]: device davinci_mdio.0:00, driver 
Micrel KSZ8081 or KSZ8091
davinci_mdio davinci_mdio.0: phy[1]: device davinci_mdio.0:01, driver 
Micrel KSZ8081 or KSZ8091
davinci_mdio davinci_mdio.0: resetting idled controller
Micrel KSZ8081 or KSZ8091 davinci_mdio.0:00: failed to disable NAND tree 
mode
Micrel KSZ8081 or KSZ8091 davinci_mdio.0:00: attached PHY driver [Micrel 
KSZ8081 or KSZ8091] (mii_bus:phy_addr=davinci_mdio.0:00, irq=-1)


After soft-rebooting the MDIO uses a different PHY mask fffffffd, 
detects correctly only one PHY at address 1 (this is the default 
address) and the networking works:

davinci_mdio davinci_mdio.0: Runtime PM disabled, clock forced on.
davinci_mdio davinci_mdio.0: davinci mdio revision 1.5
davinci_mdio davinci_mdio.0: detected phy mask fffffffd
libphy: davinci_mdio.0: probed
davinci_mdio davinci_mdio.0: phy[1]: device davinci_mdio.0:01, driver 
Micrel KSZ8081 or KSZ8091
davinci_mdio davinci_mdio.0: resetting idled controller
Micrel KSZ8081 or KSZ8091 davinci_mdio.0:01: attached PHY driver [Micrel 
KSZ8081 or KSZ8091] (mii_bus:phy_addr=davinci_mdio.0:01, irq=-1)


I'm wondering what the problem is and why the PHY mask is different 
after power-up.
Also it's not clear to me why this set-up worked with kernel 3.17 even 
if it was detecting the PHY twice exactly the same way.
How does the mask relate to the PHY address and how is it calculated?

Thanks
Petr