[meta-xilinx] Help with ethernet0 device tree node

[Nathan Rossi]

On Sat, Jul 30, 2016 at 6:49 AM, Edward Wingate <edwingate8 at gmail.com> wrote:
>
> Thank you Mike.  As I suspected, it's still broken when changing link speed that way.
>
> If anyone would confirm their Linux built using meta-xilinx can change/re-negotiate eth0 link speed from 1Gbps to 100Mbps, I'd appreciate it very much.  I'm using a custom Zynq-7020 board and the xemacps driver.  As my original message shows, xemacps driver thinks it is successful in changing the clock speed to 25 MHz for 100 Mbps operation.
>

I tested this with both the emacps and the macb driver (linux-xlnx
kernel v2016.2, on a ZYBO). Both advertise and link correctly with a
100M switch and forced advert 100M with a 1G switch, and packets are
transmitted and received correctly.

If you are having issues with this before diving into the board/hw/etc
testing double check your clock setup (and that it is propagated to
FSBL/SPL correctly), and/or EMIO setup if you are routing through PL.

>
>
> On Fri, Jul 29, 2016 at 1:20 AM, Mike Looijmans <mike.looijmans at topic.nl> wrote:
>>
>> On 29-07-16 09:21, Edward Wingate wrote:
>> > On Thu, Jul 28, 2016 at 10:15 PM, Mike Looijmans
>> > <mike.looijmans at topic.nl> wrote:
>> >>
>> >> If you use ethtool to change the speed, only change the autonegotiation mask
>> >> (0x0F for 10/100 only). Just forcing the speed to 100 usually doesn't work
>> >> because without negotiation enabled, the other side won't know about it.
>> >
>> > What ethtool options will set the autonegotiation mask?  I only see
>> > options to turn on/off autonegotiation.  I will try, but regardless,
>> > starting up plugged into a 100Mbps switch, or unplugging from 1Gbps
>> > switch and plugging into 100Mbps switch also doesn't work.
>>
>> To go to 100Mbps mode:
>>
>> ethtool -s eth0 advertise 0x0f
>>
>> Back to gigabit:
>>
>> ethtool -s eth0 advertise 0x3f
>>
>>
>> On the mpsoc this is broken too, but I guess that's just work in progress...
>>
>> root at zcu102-zynqmp:~# ethtool -s eth0 advertise 0x0f
>> macb ff0e0000.ethernet eth0: link down
>> macb ff0e0000.ethernet eth0: unable to generate target frequency: 25000000 Hz

If you are using the in kernel device trees for zcu102,.they currently
have fixed 125MHz clocks for the gems.

https://github.com/Xilinx/linux-xlnx/blob/master/arch/arm64/boot/dts/xilinx/zynqmp-clk.dtsi#L123

Regards,
Nathan

>>
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>> Kind regards,
>>
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>>
>> Mike Looijmans
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