[U-Boot] Ping failure

[Alexander Weidinger]

Hi Paul, hi everyone,

we had the same problem with our olinuxino-a64, but we were able to
solve it by using an old patch series proposed by Icenowy Zheng.

We extended the *.dts with content of the current torvalds/Linux master
branch to contain an emac configuration, which basically results in the
same changes you did. [0]
Additionally We adapted the patch series from [1] for the current
v2018.11-rc3 branch of denx/U-Boot. [2]
When not applying the patch series, the 'tx-delay-ps' option seems to
have no effect on the driver - at least we didn't find reference for
this in the code.

After this we are able to use DHCP and boot our board via TFTP.

The patch series is in the state 'Changes Requested' and it seems there
was no activity for quite some time. Nonetheless this seems to fix the
problem for us.
As a side note - this patch series seems also to be necessary for the
BananaPi-M3, which uses the same Ethernet driver but a different PHY
(Realtek instead of Micrel).

Best regards

Alexander Weidinger

[0]:
https://github.com/argos-research/u-boot/commit/546105fe859a5199b9533fbc0137b9328935bdba
[1]:
https://patchwork.ozlabs.org/project/uboot/list/?series=&submitter=71295&state=*&q=emac&archive=both&delegate=
[2]:
https://github.com/argos-research/u-boot/commit/f2a8eda9432c2d785ae446509f104de8b1492dd6