[U-Boot] [PATCH] Add CONFIG_GMAC_TX_DELAY=4 for OlinuXino Lime2

[Michael Haas <haas@computerlinguist.org>]

On 03/15/2016 07:09 PM, Karsten Merker wrote:
> On Tue, Mar 15, 2016 at 06:41:39AM +0100, Michael Haas wrote:
>
>> This change is required to get GBIT Ethernet to work
>> reliably on my board. Without CONFIG_GMAC_TX_DELAY=4, the connection
>> suffers severe packet loss and SSH becomes unusable.
>>
>> --- 192.168.1.1 ping statistics ---
>> 100 packets transmitted, 100 received, 0% packet loss, time 19842ms
>> rtt min/avg/max/mdev = 0.260/0.334/0.527/0.038 ms
>>
>> I have also tried CONFIG_GMAC_TX_DELAY=3, which still
>> yielded 11-13% packet loss.
> Hello,
>
> unfortunately this change doesn't solve the gigabit issues
> on my LIME2 - it even seems to make them worse on my board.
>
>
> Could you perhaps try netbooting a kernel with your LIME2?
> I would be interested in knowing whether that works on your
> board (with CONFIG_GMAC_TX_DELAY=0/4).
>
>
Hello Karsten,

I just tried netbooting the debian installer: it didn't work, just as
you said.

Even worse: I noticed I had not installed my patched u-boot at all when
I ran the ping test above! With my patch, the kernel would not download
at all.

So the patch is wrong and I'm sorry for having wasted everyone's time here.

I won't give up yet, however. The fact still stands that at some point,
I was able to use GBit Ethernet
without any issues in Linux, possibly after a warm reboot.

For (my) future reference, I used these commands:

--
setenv bootargs console=ttyS0,115200 rootwait panic=10
setenv autoload no
dhcp
setenv serverip 192.168.1.170
tftpboot ${scriptaddr} /debian-installer/armhf/tftpboot.scr
source ${scriptaddr}
--

I'll be playing around with the value a bit more to find the "best"
value for netbooting from a cold state, then try to get it
to work within Linux itself. Perhaps there are also some clock adjusts
to be done from within the DTS.

Sorry again!

Michael